Authentication through db link results in ORA-02074: cannot SET NLS in a distributed transaction

Hi 
Im new to APEX. Our EBS and APEX are in two databases and im communicating between the two dbs using db links.

Im trying to access APEX via menu functions in EBS and Im authorizing using the below piece of code in a Authorization scheme as per the EBS extension white paper.

if l_resp_id<>0

  xx_apex_global.apps_initialize@APPS_DBLINK(  l_user_id, l_resp_id

                                                        , l_app_id, l_sec_group);

 else

 RETURN FALSE;

 end if;

 RETURN xx_apex_global.function_test@APPS_DBLINK(l_func_name );

when running the application im getting - "ora_sqlerrm: ORA-20001: Oracle error -20001: ORA-20001: Oracle error -2074: ORA-02074: cannot SET NLS in a distributed transaction"