Private Sub ComboBox1_Change()
If Sheets("SYS").Range("A1:A18").Find(ComboBox1.Value ) = False Then
MsgBox "You have entered a invalid choice. Please make a valid
selection to continue.", vbCritical, "- INVALID SELECTION ERROR -"
ComboBox1.Value = ""
Exit Sub
End If
End Sub

The idea is to make it so if someone types in a drop down box and its
not one of the values they could select from...the application will
popup with an error message. My logic makes perfect sense to me but
VBA is having a hard time accepting it...any ideas as to why? Thanks
alot!