Error Field 'PSTYV' cannot be changed when item cat.changed in CRM Order.

Hello All,

I have created an order with one line item (item category -ZL2C)in SAP CRM. When i went into change mode and chaged the item category from ZL2C to ZTAO and saved, it is throughing an error "Field 'PSTYV' cannot be changed, ITEM_IN 000010 ready for input (Notification I V1 739)".

In R/3 , item category is in grey mode with intial item category- ZL2C and not replicated the latest item category-ZTAO.

Could anyone through some light on this how to change the item category and what are all the areas do i need to check ?

hanks in advance.

Cheers

Sreedhar