Was this working earlier? If so, could you re-apply your license and try again? If it still does not work (and from what you describe) I suspect that you may have a QlikView NPrinting Server license issue. Perhaps you are using a Demo/Eval license and the TIMELIMIT has been reached? Please use the Partner Portal to contact Qlik Qoncierge services to sort that out. Here is a link: http://www.qlik.com/support
If in fact you have a valid license and you are just trying to get NPrinting Server to work for the first time please follow this guide that explains how to troubleshoot the most common issues: https://community.qlik.com/docs/DOC-8447
Let us know how it goes.