Useless rug grippers!

I needed an anti-slip pad for my Anti-fatigue foam rug in the kitchen. So I went to Dollarama and bought a box of eight Rug Gripper made by Duramax. They worked for two days only! The Grippers sticks to the floor but not on the rug. Useless! The box reads “Keeps rugs and mats in place. No sticky residue. Press and stick. As seen on TV.”