My 9th lvl TH/2 lvl Wiz recovers traps, but can't use them. What gives? Nothing happens when I put them on the floor or use the radial view to enable them. Do I need to put points into the craft trap skill?

IIRC, you use the trap in your inventory, then use the mouse to click on where you want to place it. You don't just drop it on the floor...

You don't need craft trap to lay traps.

You do need the skill set traps though.

Sounds to me like you just don't know how to do it though.

You right click on it from your inventory and from the radial menu should have the option to set it.