Hi Nazir,
unless you already implemented checks using the new utilities check framework, the error in
me->execute_checks
should be no problem. AFAIK there is an exception raised if no checks are defined. Instead, please check if an error occurs in the different methods of class CL_CRM_IU_PR_CNTR_END_HD and CL_CRM_IU_PR_CNTR_END.
To change the date simply set the date ISURQCONTEND on the contract item after the creation of the process manager.
Christian