Symptom: When attempting to print to a printer named with an apostrophe (including Datamax-O'Neil brand), nothing prints, and no error is given. If you watch the See What's Printing window, the print job doesn't even appear in the print queue.

If you set Labeler to verbose logging, the log file includes this error:
ERROR       | Class: Wasp.WaspPrintEngine.PrintEngine, Method: PrintToPrinter, Error Description: PrintTicket XML is not well-formed. The prefix of '' in the Option attribute 'name' does not map to a valid URI.

Cause: The apostrophe (') in the printer name breaks Labeler's ability to communicate with the printer. The printer name is truncated at the apostrophe, so Windows looks for a printer that doesn't exist (for example, a printer named Datamax-O).

Resolution: In Windows's Devices and Printers, right-click the printer and go to Printer Properties. In the General tab, remove the ' from the printer name, or give it a different name altogether, then click OK. Note that if the printer has been shared, the other PCs may need to reconnect with it. Close and reopen Labeler and attempt to print again, and now it should work properly.