Unable to cancel Dropship PO

Hello,

We need to cancel Dropship PO as a single PO has been created against Multiple Sales Order.

We were able to cancel a few POs but when trying to cancel others from the Manage Order it gives us the error as Cancellation Must be Initiated from Order.

How can this be resolved? we need to cancel the PO to create new PO against sales Order. And if this cannot be cancelled, why were we able to cancel others.

Thanks,

Prashant