Forum:Trap Stun VS Trap Jammer during the Battle Phase

Hello there ! I have some problems with my brother right now. During my brother's Battle Phase, I activated Dimensional Prison against his attack, he activated Trap Stun and I answered thanks to Trap Jammer. As it was a Chain, Trap Jammer was the first effect to resolve and activate, but my brother doesn't agree... I try to explain him that Trap Jammer is a Counter Trap Card, and that, moreover, we were in a Chain....

Was I wrong to play Trap Jammer ? Or was I totally right to consider this as a Chain ?