Not all tasks from GP appear in UWL, some are missing

Hi

We are using GP for building the workflows and UWL as a front end to access the tasks. However all the tasks that are in GP do not appear in UWL. Tasks older than 4 months seem to disappear from UWL on daily basis. Every day we see that the older tasks have disappeared. Is there some configuration / system setting that controls this? However all the tasks are still avaliable and can be viewed through GP.

Pls send any configuration details that you know controls this.

Thanks

Arvind