Printing problem

I have scheduled to print a numerous of report in mid-night. But, I found that some reports have not been printed out.
Then, I checked the file /var/spool/lp/log and found that all reports have been submitted to print queue.

Could anyone tell me what can be done to ensure all print jobs can be printed out successfully?
Thanks!

Notes: The printer is network printer.

Based on what you are saying this is a user issue.

Are you printing a banner or separator page? Are any of those reports one page or less so that a person separating them could put 2-3 reports in one pile thinking it is just one report? Most reports are only looked at when there is a problem, or maybe at month end. Hoever users WILL complain if they don't get the report.

Here's why - if the queue is not stalled, and the job is in the log, it printed. Period.
You have a user perception or behavior problem not a printer queue problem. Where the physical report went is not your problem syadmin-wise.

Thank you!
I found that it may be caused by printer insufficient memory.