I am a newbie in excel VBA.
I attempt to set a condition to test cells property.
1. The cell have 5 characters
2. The first 2 characters are letters
3. The last 3 characters are numeral

Test the contents of your Cell like this...

If ContentsOfCell Like "[a-zA-Z][a-zA-Z]###" Then
' cell contents are 2 letters followed by 3 numbers
End If

Rick