Here is an update of a class I use to import an Excel sheet into a dataset. This is based on a framework but the core of the code should be able to be used as is. Note that I have added a oField collection that can be filled with the AddField() method so to make sure all the required fields are present in the Excel sheet before starting the import.

Imports System.Data.OleDb
Imports System.Text

Public Class Import

    Public cMessage As String = ""
    Public cSource As String = ""
    Public cWorkbook As String = "Sheet1"
    Public nCount As Integer = 0
    Public nDuration As Double = 0
    Public nLanguage As Integer = 1
    Public oDataAdapter As OleDbDataAdapter = Nothing
    Public oDataSet As DataSet = New DataSet
    Public oRows As DataRowCollection = Nothing
    Private cASheetCalledSchemaIsNotFound As String = ""
    Private cTheExcelSheetShouldBeInAXLSFormat As String = ""
    Private cTheFieldDoesNotExist As String = ""
    Private oApp As Framework.App = Nothing
    Private oConnection As OleDbConnection = Nothing
    Private oField As Collection = New Collection
    Private oProcess As Framework.LXProcess = Nothing

    ' This is when we access the class in a desktop mode
    Sub New(ByVal toApplication As Framework.App)
        oApp = toApplication
        nLanguage = oApp.nLanguage
        Initialize()
    End Sub

    ' This is when we access the class in a Web or Web Service mode
    Public Sub New(ByVal toProcess As Framework.LXProcess)
        oProcess = toProcess
        oApp = oProcess.oApp
        nLanguage = oProcess.nLanguage
        Initialize()
    End Sub

    ' Initialize
    Private Function Initialize() As Boolean

        ' Based on the language
        Select Case nLanguage

            ' English
            Case 1
                cASheetCalledSchemaIsNotFound = "A sheet called ""Schema"" is not found."
                cTheExcelSheetShouldBeInAXLSFormat = "The Excel sheet should be in a XLS format."
                cTheFieldDoesNotExist = "The field ##Field## does not exist in the Excel sheet."

                ' French
            Case 2
                cASheetCalledSchemaIsNotFound = "Une feuille appelée ""Schema"" est introuvable."
                cTheExcelSheetShouldBeInAXLSFormat = "Le fichier Excel doit être dans un format XLS."
                cTheFieldDoesNotExist = "Le champ ##Field## n'existe pas dans le fichier Excel."

                ' Spanish
            Case 3
                cASheetCalledSchemaIsNotFound = "No se ha encontrado una hoja llamada ""Schema""."
                cTheExcelSheetShouldBeInAXLSFormat = "El fichero Excel debe estar en formato XLS."
                cTheFieldDoesNotExist = "The field ##Field## does not exist in the Excel sheet."

                ' Portuguese
            Case 4
                cASheetCalledSchemaIsNotFound = "A sheet called ""Schema"" is not found."
                cTheExcelSheetShouldBeInAXLSFormat = "The Excel sheet should be in a XLS format."
                cTheFieldDoesNotExist = "The field ##Field## does not exist in the Excel sheet."

        End Select

        Return True
    End Function

    ' Import from Excel
    Public Function ImportFromExcel() As Boolean
        Dim lcConnection As String = ""
        Dim lcField As String = ""
        Dim lnDateNow As Double = 0
        Dim lnDateNow2 As Double = 0
        Dim lnElapse As Double = 0
        Dim loData As Framework.Data = Nothing
        Dim loLogData As Framework.LogData = Nothing
        Dim loObject As Object

        ' Get the proper definition as per the current scope
        If oProcess Is Nothing Then
            loData = New Framework.Data(oApp)
            loLogData = New Framework.LogData(oApp)
        Else
            loData = New Framework.Data(oProcess)
            loLogData = New Framework.LogData(oProcess)
        End If

        ' Reset the values
        cMessage = ""
        oRows = Nothing

        ' Start time
        lnDateNow = Date.Now.Ticks

        ' Initialization
        lcConnection = "provider=Microsoft.Jet.OLEDB.4.0; data source='" + cSource + "'; Extended Properties=Excel 8.0;"

        ' Assign the source directory
        oConnection = New OleDbConnection(lcConnection)

        ' Select the data from Sheet1 of the workbook
        oDataAdapter = New OleDbDataAdapter("Select * From [" + cWorkbook + "$]", oConnection)

        ' Try to import the data
        Try
            oDataAdapter.Fill(oDataSet)
        Catch loError As Exception
            cMessage = loError.Message

            ' Try to extrapolate
            Select Case cMessage

                ' External table is not in the expected format.
                Case "External table is not in the expected format."
                    cMessage = cTheExcelSheetShouldBeInAXLSFormat

                    ' 'Schema$' is not a valid name.  Make sure that it does not include invalid characters or punctuation and that it is not too long.
                Case "'Schema$' is not a valid name.  Make sure that it does not include invalid characters or punctuation and that it is not too long."
                    cMessage = cASheetCalledSchemaIsNotFound

            End Select

            Return False
        End Try

        ' Record count
        nCount = oDataSet.Tables(0).Rows.Count

        ' If we have some records
        If nCount > 0 Then

            ' Adjust to our default name
            oDataSet.Tables("Table").TableName = "Temp"

            oRows = oDataSet.Tables("Temp").Rows()

            ' If we have a field to verify for before proceeding
            If oField.Count > 0 Then

                ' For each field
                For Each loObject In oField

                    ' Initialization
                    lcField = Trim(loObject(1))

                    ' If the field does not exist
                    If Not loData.FieldExist(oDataSet, "Temp", lcField) Then
                        cMessage = oApp.StrTran(cTheFieldDoesNotExist, "##Field##", lcField)
                        Return False
                    End If

                Next

            End If

        End If

        ' End time
        lnDateNow2 = Date.Now.Ticks

        lnElapse = ((lnDateNow2 - lnDateNow) / 10000000)

        ' Just in case
        If lnElapse > 999.999 Then
            lnElapse = 999.999
        End If

        nDuration = lnElapse

        ' Add the log
        loLogData.cLog = "Select * From [" + cWorkbook + "$]" + oApp.cCR + oApp.cCR + _
         "Duration: " + oApp.GetFormatValue(nDuration, , 4) + " " + _
         "Count: " + nCount.ToString + oApp.cCR + oApp.cCR
        If Not loLogData.AddLog() Then
        End If

        Return True
    End Function

    ' Add a field in the collection which will be verified at first to make sure it is part of the Excel file
    ' expC1 Table
    Public Function AddField(ByVal tcField As String) As Boolean
        Dim lcField As String = ""
        Dim loObject(1) As Object

        ' Initialization
        lcField = Trim(tcField)

        ' Initialization
        loObject(1) = tcField

        oField.Add(loObject)

        Return True
    End Function

End Class

And, from the client:

        Dim loImport As Framework.Import = New Framework.Import(oProcess)

        ' Assign the Excel file
        loImport.cSource = oUpload.cFile

        ' Assign the workbook
        loImport.cWorkbook = "Schema"

        ' Add each field which is mandatory
        loImport.AddField("PrimaryKey")
        loImport.AddField("Name")
        loImport.AddField("NoProvince")
        loImport.AddField("NoCountry")

        ' If we cannot import the data
        If Not loImport.ImportFromExcel() Then
            cMessage = loImport.cMessage
            Return False
        End If

        ' For each row
        For lnCounter = 0 To loImport.nCount - 1
            loRow = loImport.oRows(lnCounter)