Getting error status not allowed

Hi Frds

I am using CRM_STATUS_CHANGE_EXTERN_OW  to update the header status.

LIKE:

call function 'crm_status_change_extern_ow'

exp

          objnr = h_guid

           user_status = 'E0005'

EXPECTIONS .

but this when FM executed it gives 'Status not allowed' error, how to resolved it?.

Please do the need full ASAP.

Thanks

Imran