Issue in BAPI_PO_CHANGE

Hi Gurus,

I am using the BAPI_PO_CHANGE to change the account assignment categeory from blank to cost center 'K'. The BAPI is throwing an error :

"Account 50010101 requires an assignment to a CO object".

but I have already passed the CO objects.

BTW,

1: i have simulate the data which passed via ME22N,it work perfectly.

2:i also check the data in debug mode.it has been passed into the function correctly

3:i also populated the parameters into the BAPI import parameters poaccountx

4:i try to change the other datas such as delivery schedule,price,quantity.the BAPI also work.

does anybody have any hints to solve this issue? kindly thanks in heart.