Run-Time Error '13' Type Mismatch - ACCESS DATABASE

Question

I am trying to compare two text fields txtTrailerNumber and txtSealNumber to the database table Tab_TrailerDetails. [TrailerNumber] and [SealNumber] as listed in the table.

I am trying to get the database to look at the trailer number entered into the form, and if it finds a duplicate value it then looks at the seal number entered into the form. If both values have a duplicate found in the table it should throw up the Msg_Box error code.

Private Sub txtSealNumber_AfterUpdate()

Dim NewTrailer, NewSeal As String
Dim stLinkCriteria As String


'Assign the entered Trailer Number and Seal Number to a variable
NewTrailer = Me.txtTrailerNumber.Value
NewSeal = Me.txtSealNumber.Value

stLinkCriteria = ("[TrailerNumber]='" & NewTrailer & "'" And "[SealNumber]='" & NewSeal & "'")

If Me.txtTrailerNumber = DLookup("[TrailerNumber]", "Tab_TrailerDetails", stLinkCriteria) Then

   MsgBox "This trailer, " & NewTrailer & ", has already been entered in database," _
              & vbCr & vbCr & "along with seal " & NewSeal & "" _
              & vbCr & vbCr & "Please make sure Trailer and Seal are not already entered.", vbInformation, "Duplicate information"
     
'undo the process and clear all fields
    Me.Undo
    

End If

End Sub

Answer 1

The cause of the error is that you have a logical keyword, notably AND inside a string expression. Change your code to

stLinkCriteria = ("[TrailerNumber]='" & NewTrailer & "' And [SealNumber]='" & NewSeal & "'")