As Musher said, one snow and one night don't leave much time to generate sign. And I'll agree that traps in the back of the truck don't catch anything but traps set on poor locations don't catch anything either and it takes a lot of muss and fuss to get those traps set, only to look empty traps. In this case, empty traps in the back of the truck are easier to look at than empty traps set on poor location, especially now that snow and freezing weather is extant.
The problem here is that you don't quite know how to identify good location yet. It in fact takes a few years of trapping, and a few years of trial and error to begin to understand that. So for somebody to just tell you to set in good locations, while good advice, is meaningless if you don't know where those locations are.
I would advise you to wait a few days, if possible, and check the snow again. By that time, the critters will have moved around a little bit. Then they will tell you where the good locations are.
Endeavor to persevere.