Batch Job issue

Hi,

I have Job scheduled for VL06P t.code to create TO`s automatically as soon as deliveries are created.Next day succesfully job ran leaving a single To without creating for a delivery.

When manually created the TO it ha successfully created without any error.Why there is an issue in job and not while manually creation.

How can I see why a document is failed in Job run...for so and so reason the document has not created??