To print you must have credit in your account. There are a number of ways to add credit to your account.
You will need to have enough funds in your CPAS account to print a print job. For example, if you try to print a 15 page black and white document and only have $1.00 on your account the print job will not proceed. Your print account cannot have a negative balance.
Please note that CPAS does not provide refunds for any print credit left in your account. If you have credit that you do not plan to use you can transfer that credit to another person.