This error is typically caused by one of three reasons.
1.) You purchased and authorized AcroPlot only. AcroPlot users do not have the ability to print directly to the the PDF-XChange for AcroPlot Pro printer driver. Only AcroPlot Suite (formerly AcroPlot Pro) users are allowed to do that. You can upgrade your product to AcroPlot Suite by logging into your account. Then you can select the AcroPlot licenses you would like to upgrade and hit the Purchase Maintenance button. This will then give you an option to upgrade the licene(s) to AcroPlot Suite.
2.) The other reason is that the registration of the PDF-XChange for AcroPlot Pro printer driver did not work when you registered AcroPlot Suite. The video below will explain this in more detail.
3.) The third reason is if you are running AcroPlot Suite in evaluation mode. In evaluation mode we do not allow use of the printer driver directly without a watermark. Only when converting directly through our AcroPlot Pro program will we remove the watermarks during your 30 day evaluation trial.