How to pass value to 'TYPE REF TO' variables in SRM

Hi All,

I am new to SRM ABAP , can you please help out on how to pass value to a parameter

Interface : /SAPSRM/IF_PDO_DO_LIMIT

Method : ADD_ITEM_LIMIT

Data : lo_msg_consumer TYPEREFTO   /sapsrm/if_pdo_msg_consumer.

CALL METHOD me->add_item_limit

            CHANGING

              ct_limit_item      = lt_limit_item

              co_message_handler = lo_msg_consumer.

Kindly let me know how to pass value to lo_msg_consumer.As during runtime its not accepting the BLANK value to lo_msg_consumer as its mandatory parameter and gives dump.

Thanks,

Nalini.