Selection Screen Validations

Hi,

I have a requirement, where I have to create selection screen with 5 radio buttons. Clicking on different radio buttons, will enable / disable few fields from display. Here the problem is there are few mandatory fields. So, if I am changing the radio button selection, standard is throwing the error for entering values in all mandatory fields.

Is there any way to avoid this error message when there is a change in radio button selection and throw the message when user presses enter key or executes the program using F8?

Thanks in Advance,

Phani.