Three points, and PM or call me if you still have no luck:
1: Got to have cell service. Can create issues in Georgia mountains and remote areas where cell service is iffy, but the US Interstate system is supposed to have 100% coverage.
2: Got to have created a trip on the Spotwalla site. Select start/end times; make sure the end doesn't occur before the beginning (DAMHIK); and make sure 'sharing' settings are cool. You can create the trip afterwards, but the phone/Spot device must have been dropping bread crumbs during your trip. (You can also go in after your return, and create a new trip that shows .... for example ... your route for only a few hours out of a multi-day trip.)
3: Got to be outside your security zones. FredW's half right on that point: No spots will be shown inside a security zone, but you create them, set a center point, and establish a radius. For the record, even special messages will not be posted inside a security zone.
I have created security zones around myself and my loved ones. They're not centered on the house (I can be super-paranoid) and of varying sizes. The Spotwalla display will show the last spot outside the zone, then the next subsequent spot outside the zone even if it's 24 hours later. This can cause some concern for those following your track: "His location hasn't moved in an hour, and he was less than 2 miles from Mom's house."