Testing For Duplicate Entry

I have a form that information is entered in. At the end the user can then save the information in a spreadsheet by pressing a command button. The updating to the spreadsheet works, it is the part where the last entry is tested against the info on the form to prevent a duplicate entry that do not work.

I have tested that the program reads the info from the spreadsheet (see the commented lines).

I can attach the whole spreadsheet, but some of the entries on the form are linked to another spreadsheet that make it a bit cumbersome to attach two files.

VB:
Private Sub cmdUpdate_Click()
Dim lRow As Long
Dim ws As Worksheet
Set ws = Worksheets("TonnageInput")

[Code] .....