There is a utility tool buried in the Dymo install directory under Support called LWSupport, usually located here:
C:\Program Files\DYMO\DYMO Label Software\Support
1. Launch LWSupport by double clicking on LWSupport.exe
2. Select Remove DYMO Printer Drivers
3. Accept defaults
This has fixed some problems in the past where everything looks correct but the Dymo printer just won't print from the Dymo software.