Report works locally failing on server (PLS-00382: expression is of wrong type)

I have a simple report running against an Oracle Function (it also works with an SP with same logic) that works fine in eRD or locally on my machine (the rox) however the same does not work on out Actuate server with the error below. Both are using the same ActuateDD 5.3 driver and same credentials, db etc.

Status No: 1 :
Basic Error: 1011
Module: afc\db.bas
Line: 189

Database Error
2: Error generated by the connected data source ...
6550: [SQL State] S1000: [ActuateDD][ODBC Oracle Wire Protocol driver][Oracle]ORA-06550: line 1, column 17:
PLS-00382: expression is of wrong type
ORA-06550: line 1, column 9:
PL/SQL: Statement ignored


the function is:

create or replace
FUNCTION ACT_DUMMY_FUNC
(
CIN IN STRING
)
RETURN SYS_REFCURSOR
AS
my_cursor SYS_REFCURSOR;
BEGIN
-- ignoring the CIN parameter for now

open my_cursor for select * from OWNER.ACT_DUMMY_DATA;
return my_cursor;
END ACT_DUMMY_FUNC;