Cancelling a release for collection

Hello,

I am trying to cnacel an item that was release for collection.

The docuement is partially cleared by write off and partially open.

The collection status of the open item is 7: receivable partially paid and partially not collectible

I can't unrelease it using fp03E - I'm getting a message that 'Undo only possible with status Released, Recalled, or Reversed'.

What can I do ?

Thanks,

Vered