Unknown function/tuple constructor

Hi, I’m working writing a query (query_main) calling a sub query ( query_main_sub(SET<VERTEX>usersSetA, SET<VERTEX>usersSetB) ) in it which expects 2 sets of vertices.

I’m able to call query_main_sub from query_main as long as I perform all the SELECT on user vertices only eg., SELECT s FROM user:s.

But the moment I add a SELECT on user connected to other vertices eg., SELECT s FROM user:s -(_>)- case:t, I get error “ Error: unknown function/tuple constructor “

Does anybody why am I getting that error? Or how to fix this issue?