Hi,

I don't think your extension method worked as intended. Try:

'ExtensionAttribute
<System.Runtime.CompilerServices.Extension()> _
    Public Function IncludesCode(ByVal sc As e_SecurityCodes, ByVal DocSecurityValue As e_SecurityCodes) As Boolean
         If sc.HasFlag(DocSecurityValue) Then
            Return True
        End If
        Return False
    End Function

Then for the Click:

Dim results As List(Of ListCol) = New List(Of ListCol)()

        Dim l1 As New ListCol()
        l1.Id = 1
        l1.SecurityCodes = e_SecurityCodes.DMS_Accounting_AP
        results.Add(l1)

        Dim l2 As New ListCol()
        l2.Id = 2
        l2.SecurityCodes = e_SecurityCodes.DMS_Accounting_AR
        results.Add(l2)

        Dim result_Match =
            (From x In results Where x.SecurityCodes.IncludesCode(e_SecurityCodes.DMS_Accounting_AP) Select x).ToList()

(I mocked your ListCol class like so):

Public Class ListCol
    Private _securityCodes
    Public Property SecurityCodes As e_SecurityCodes
        Get
            Return _securityCodes
        End Get
        Set(ByVal value As e_SecurityCodes)
            _securityCodes = value
        End Set
    End Property

    Private _id
    Public Property Id As Integer
        Get
            Return _id
        End Get
        Set(ByVal value As Integer)
            _id = value
        End Set
    End Property
End Class

Sorry if this doesn't solve the problem - done in a rush .....