Please check that you have configured your NPrinting server service account correctly:
It is likely that you do not have a dedicated NPrinting Service account and that you do not have a dedicated named CAL manually assigned to the dedicated nPrinting server service account.
If you continue to have issues after checking the above, please log a case via the Qlik Support site in order to effectively assist you with the issue.
If you do not have access to the support site, you can request access (if you have a support maintenance agreement) with the Qlik Support Qoncierge at the link below:
Never the less, checking and updating your configuration via the information above is certain to resolve your issue.