Batch Management issue- Urgent

HI SAP GURUS,

Firstly we create the material master and the we create the MTO sale order and after that we had created a prod. order of this material with the reference of sales order. earlier the user had created the material as non-batch managed material, but during the receipt of material against prod. order we neeed the material as batch managed material, now i want to make these materials batch managed.and now during making the material as batch managed the system is giveing the error

Batch management requirement cannot be changed; choose "Display errors"

The batch management requirement cannot

be changed for the following reasons:

SD documents exist (orders or deliveries) that have not yet been

processed or that have been processed only in part.

For ur info. i have mantained material master record batch mgt field mentioned inthe Workscheduling view ans sales/general planr view.

Can u pls suggest how to go abt this. Is there any solution please come out, it is critical

Thanx & Regards,

Seenu.