UDFunctions Table to Table

Hello there,

recently I try to define some UDFs which map tables to tables. Therefore I've written an hdbfunction file like this:

FUNCTION "NEO_X"."project.logic::simpleFunc" (IN val "project.structures::tt_simpleTable" )   RETURNS TABLE ( res VARCHAR(500) )  LANGUAGE SQLSCRIPT  SQL SECURITY INVOKER AS
BEGIN  RETURN SELECT CONCAT (COL1, COL2) FROM val;
END;

But this results in an error while activating it, saying that "DEV_"."val" is not defined... well of course it's not!

What am I doing wrong here?

Thanks.