Need BAPI to post Reversal in FB08 or any other methods.

Hi friends.

I used Bapi called ' BAPI_ACC_GL_POSTING_REV_POST ' for Reverse the Document in TRansaction FB08,

But it is not successfully working for me.

The BAPI is asking for the values to be given in input for the following fields.

I need more information about the fields,

Fields name : Logical system (obj_sys),

Previous Reference Document (obj_key_r).

These two fields are mantadory.

Do I have any other method to post the reverse entry in transaction code FB08 ?

Or please guide me how to go about the BAPI mentioned above.