>>In String you need to omit ?. String is not a simple type like integer, for example. So, you can pass null without declaring string?, just declare parameter as string.
>
>So, the adjustment I made is this:
>
>

>        ' Avoid to receive a null
>        ' expC1 Value
>        Public Function GetNonNullable(ByVal tcValue As String) As String
>            Dim lcValue As Integer = ""
>
>            ' If we have a value
>            If Not tcValue Is DBNull.Value Then
>                lcValue = tcValue
>            End If
>
>            Return lcValue
>        End Function
>

You're dim'ing lcValue as integer but filling it with a string.... ???