SRM PO Workflow Unable to determine approvals of change po .. it works fine while create PO

Hi Masayuki ,

Help regarding PO Process control workflow..

I i have 3 levels of process control workflow .. to determing purchasing group manager of user level 1 approval .. then manager of level 1 i.e manager level 2 and then .. manager of manager 2 i.e manager level 3 ..

i am using below standard  process levels

RR_PURCHASING_MANAGER

RR_MANAGER_OF_MANAGER

RR_MANAGER_OF_MANAGER

It works when we are creating/Changing Po with user where purchasing group is having purchasing group manager.. i.e level RR_PURCHASING_MANAGER

But if i try to change PO  (Change aftr ordering po and all levels of approls ) with manager 2 RR_MANAGER_OF_MANAGER

then i am not able to determine level 2 and level 3 approvals ...

Simillary if i try to change po with manager 3 i am getting level 1 and level 2 approval but nt getting level 3 approval..

Error massage

"Strategy did not determine any approval RR_PURCHASING_MANAGER"

and if i change PO with initial buyer (Who created PO earlier ) i am getting all approvals..

and if i try try to create or copy PO from manager level 1 then also i am getting above error for all levels ..

Is it happening because of org structure issue ?

Please help

Thanks

SL