wrong profit center in sales doc

hi,

Clent says that the billing doc is posted to wrong profit center. I checked the Pc in material master is say XX but in billing doc another PC YY is getting updated...checked Sales Order YY is there also. In some of the billing docs profit center is catching correctly as per Material Master. System is 4.7

What may be reason for this how can we correct it??

Thanks and regards

ramesan