Check Box in UDO Form

Hi !

I have a form made with Screen Painter and i put in it a check box. The field is binded to my UDO table. When i click on add in my form all the data are added in my UDO table and the values for my checkbox are Y or null in the Table.

My question is that i would like to catch an event when i click on add to print a message on screen when my check box is checked .

Can you help me with code please...

Thanks