Nothing was connected to our ceiling fixture (so I can't see what the connection used to be). There is one black wire, one red wire and three white wires (the white wires are twisted together into one tip). I connected the white wires to one wire on our fixture, the black wire to the other fixture wire and I capped the red one. The light turned on. However, nothing I'm doing to the wall switch/dimmer is working. I opened the dimmer switch and there's a similar 3-white wire, black wire, green and wire configuration. Can anyone help me sort this out? Is my dimmer switch dead? are the wires in the wall dead? Thank you.

Nina