Characteristic values are not copying while confirmation of production order.

Hi

We are using auto goods receipt concept and one of the batch class characteristic is with MCH1_HSDAT. This char value is normally updating when we do the confirmation of production order. But some of the times this char MCH1_HSDAT is not updating while confirmation..and getting the error " error on batch characters updation".. what might be the cause..

Regards

Kesava