This can be due to low or smudgy toner, or the printer or print server generally misbehaving.
If this happens to your print job, Helpdesk can refund your print quota to compensate. Simply bring the pages with you so that we can verify the problem, and we can put it though for you straight away.
Please note that pages are only deducted from your quota after the printer has completed the job.
If a job simply fails to print, or the printer crashes halfway through, you will not be charged at all, so there will be nothing to refund.