I recently took an old ceiling fan off and replaced it with a new one. The wiring is the same white, blue, black. I hooked it up white on white and blue/black on black. The fan has four lights attached but, it barely works. When the fan is on the lights dim down. On the highest speed of the fan the lights are almost completely off. When the fan is off the lights work fine. Any clues on what the problem may be? Thanks for any help.

What gauge wire is supplying the fan?