Advanced Customization of Quote Entry

OK. I've been able to accomplish part of what is required. Still,
but still I'm having trouble getting this to work: I'd like to be
able to search the quotedtl.partnumber table upon entering a
partnumber is the txtPartNumber field. If the part number exist, a will display "The Part has already been quoted."

This is what I've got so far:

Private Sub QuoteDtl_AfterFieldChange(ByVal sender As object,
ByVal args As DataColumnChangeEventArgs) Handles
'// ** Argument Properties and Uses **
'// args.Row("[FieldName]")
'// args.Column, args.ProposedValue, args.Row
'Add Event Handler Code

Dim qteAdapter as QuoteAdapter = New QuoteAdapter(QuoteForm)
Dim ohaConnected As Boolean = qteAdapter.BOConnect()
Dim Success As Boolean = qteAdapter.GetByID(txtEpiCustom1.text)
Select Case args.Column.ColumnName

Case "PartNumber"

If(Success) Then"Already entered for this part")
End If
End Select

End Sub