Search Help Exit with own Selection and Dialog to choose a Value

Hi Experts,

I've created a customizing table where I've assigned a search help to one of the fields. Because the type of this field is dynamic (depending on the content of another field) I want to take over the whole search help in a search help exit. This all (displaying a dialog an choosing the value) works fine. I have only one problem: How can I pass the chosen value to the table field? I have tried a lot including changing CALLCONTROL-STEP (where I think I have to set it to 'RETURN') and put a value into RECORD_TAB, but nothing works!

Thanks in advance.