Review cart and order cart throws error "The document is released and not changeable"

Hi All,

While creating shopping cart for casual users(SRM UI add on),I try to add items to the cart.Items are added successfully.

But when i try to "Review" and "Order cart" i get an error "The document is released and not changeable" and unable to progress any further .

Any inputs on why such error occurs?

Thanks,

Regards,

Tara