LWL labels created on PC won't open on MAC version (by 2 users)

Frustrated! Created entire line of jewelry barbell labels on PC version of Dymo Label Software. Gave USB printer to wife and CD to install on her MacBook Pro. Installed fine runs fine on ALL files (DLF extension on Mac) she creates on Mac... BUT can not OPEN any of the LWL extension files I created on the PC. An absolute waste of a month of design and label creation!!! Anyone got a clue as to how to address this issue? Troubleshooting has not been successful thus far. All label files reside in correct folder in specified location. Of course simply changing the extension does not help. Could not find any reference to SAVE FOR MAC version. Help?!?!? Thanks.