hi everyone!
i created a Form using Developer 2k & table from Oracle 8i

some of the columns has attached LOV so user can select value from LOV

i have given 2 save button, one in the Form & other in Menu Option Bar

but problem is that after feeding values (some value selected from LOV) when I click the Form's SAVE button it's Alerting Message "Field Value cannot be null" & cursor Jumps to First LOV attached Column & can not be saved the row but when i click SAVE button from Option Menu Bar then it's running fine but user wants SAVE button on the Form. what is the solution
plz guide

R