From the message it looks like you are trying to resume a flow that is not currently present on the pxFlow pages of the work object. Can you provide additional details regarding the flow process? Can you show what the flow looks like and the parameters being passed to ResumeFlow?
That is the issue. If it should be there but is not you will want to review the process to see when it is removed. If it is expected to not be present, then you will want to start the flow instead of using ResumeFlow.