Confirmation Control key not allowed in MM Scheduling Agreement item.

Hi Experts ,

I am facing an issue with Confirmation control key in MM Scheduling Agreement.

Scheduling agreement already GRd without Conf-key and Now if am going to update confirmation control key as 0001.

I am getting an error "Confrmation Control key is not allowed".How can I solve this problem.Anyway i have to update the conf-key.

If you are answering me that will be very much apreciatable.

Looking forward for your answers.

Thanks,

Bala