Here are some things to try:

• Make sure the thermal printer is on and has paper. 
• If this is a non-Carswell printer, click the "..." button next to the "Print" button and make sure that it is set to "Print Document Image without Signatures". 
• Make sure that the form type in the upper right hand corner is set to "Receipt" and not "PhotoID". 
• Make sure that the correct printer is selected in the ProDoc setup -- the printer should be named "RDI_Receipt". 
• Check the local Windows print queue to make sure nothing is being held up there.  To do this go into Printers And Faxes and double-click the RDI_Receipt printer.  You can also send a document from Notepad to the printer (do not print a Windows test page to the printer). 
• If the receipt printer is not plugged directly into your workstation, make sure that the workstation the printer is attached is powered.