Getting error Incoming payment .You can not cancel Payment;one or more checks are canceled

I am trying to cancel Incoming payment document ,there are 3 checks in this document,did following steps.

1) canceled each checks which were already reconciled with Invoices.

2)trying to cancel Incoming payment getting error msg "You can not cancel Payment;one or more checks are canceled"

main purpose is to un reconcile the Invoices against these checks..