UDF Formatted Search

Hi, 

I'm trying to make a UDF that is based on the value of another UDF. Usually this is done via the $[table.column] format on standard SAP but how do I approach this with BEAS?

I tried $[beas_arbzeit.udf1] and $[dw_1.item.udf1] as the parameter for the SQL statement for the UDF4 dropdown, both are not working.

Is there a way to do this via the BEAS UDF functionality?