Workflow persistence using appfabric issue

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AppFabric

WWF

I am using appfabric to persist a xamlx workflow. The workflow should create a task and wait for my approval. Once i approve, the task status should be completed and then the workflow should execute the next step.

I configured the appfabric to unload the instance from the memory after 30 seconds.

After the workflow instance is unloaded from the memory, i try to approve the task but the workflow creates a new task and set its status to "completed" and moves to the next step but it keeps the old task as it is and its status is in progress

Is there any reason for this strange behavior??