Are you setting them back to back and closing the hole? A gopher will go into a trap to close an open hole. If you leave an open hole a mole won't go near the trap and will back fill further back.I'm hell on the gophers with the trapline traps. Never a miss. As soon as I see the mound I dig it out and set the trap(s) and within a few hours I've got a dead gopher or 2, and sometimes 3, depending on how the hole was built and structured.
I'm 0'fer with the mole traps. Zip. Zero. Nada. Can't catch a mole. Same brand of trap, just smaller, and I can't catch a cold with them.