Value Check on Selection Screen

Hello Everyone,

Just a quick question. When I use VALUE CHECK in the selection screen, the system checks the input field against the check table even when there has been no input in it. As a result, I get a error message that says 'Entry <space> does not exist in ABCD table'.

How do we enable VALUE CHECKs on input only i.e. without using the Event AT SELECTION SCREEN ??

Thanks in Advance....Jaison