Changed To Dimmer Switches and Other Lights Not Working?

I recently started switching some of my rooms to dimmer switches. I changed the kitchen switches without a problem. Then we go upstairs, and I switch bedroom #2 to a dimmer. I go to turn the power back on and notice although bedroom #2 works fine, now bedroom #3 and the bathroom lights don't work! Even when I didn't even touch them! However, all outlets in those bedrooms work. I did the entire process over. All wires are connected properly. I just don't see how changing one switch resulted in two over switches not working.

Any suggestions?

By Krista