Attempting to complete worktask, get error indicating object can only be approved by active work task

While attempting to complete a work task I am recieving an error stating the following:

"This Class of Object may only be approved via an Active WorkTask. Please ensure that the related WorkOrder is started and that the WorkTask Accepted.
(From DbEventHandler: 'ebh_approve_package')"

The user has quite clearly accepted the work task as they are now attempting to complete it and it is in their inbox.  I am stumped as to an explanation for this and I do not have access to review exactly what ebh_approve_package is doing so there is very little I can do to investigate.

Any ideas would be much appreciated.