There are several different formats for Latitude / Longitude. If you want to enter a particular format into your GPS you need to set your GPS to accept that format or convert to the format that your GPS is currently set to before entering it. Without a NAV VI if front of me, I can't tell you where in the menus to go to change the format setting in your GPS, but it's there somewhere. Keep looking, you'll find it. Or, convert to the format the GPS is currently using before entering it.
Most common formats are these:
sexagesimal degree: degrees, minutes, and seconds : 40° 26′ 46″ N 79° 58′ 56″ W.
degrees and decimal minutes: 40° 26.767′ N 79° 58.933′ W.
decimal degrees: 40.446° N 79.982° W.
jusbill