Clearing fields after value change in another field

Hi Folks,

I created a dynpro with three input fields and a attached search help.

These three fields represent a hierarchy. That means, that the entries in the fields depend on each other.

Therefore I want to clear field 2 and field 3 when I change the value of field 1. I select the new value from the search help list.

I tried to clear the fields at PAI using ON REQUEST, but the problem is, the cleared values of field 2 and field 3 are not displayed. They still contain the old value. I guess, the problem is, that I do not press enter after the selection of the new value in field 1. Is there a way how I can trigger the field transport to the dynpro after I cleared the fields? The field command transports only from dynpro to ABAP.

Thanks in advance,

Martin