Guaranteed Delivery: Expired Transaction

Our client using Integration Server601 sends documents by GD. They Expired Transaction after about 20 minutes. We have configured watt.tx.defaultTTLMins=30. We do not know why it fails? There is no timeout set on services.

I checked the logs and could not make any useful information from it. Is there any we can configure the logs to get more info.

Any way of resolving this problem is much appreciated.