Importing SD card

I have downloaded waypoints from Google Earth to an SD disk and converted it to a GPX format. But, when I insert the card into the HDS unit I can’t import it . I go to files and find the file I created, but all I get is an option to copy it. I have tried different SD cards and formated the card. Any ideas ? Thank you

I found this with Google. Sounds like that is not the format you want for importing.

How do I convert a GPX file to Lowrance?
Depending on your unit, the easiest method is to use the Lowrance GPXtoUSR Geocaching Application. This application allows you to simply select the GPX files and it will convert it to a . USR file.