I removed old switches and plugs from existing box. I installed a single pole switch for the vanity lights which is working correctly. I have installed a "double switch" for the tub light and the fan. I want to wire the light to the upper switch and the fan to the lower switch. There are four black wires available to be connected. All the white wires have been properly capped together. I have tried several times, but each change I make has one of the switches powering both the light and fan together (and the other switch does nothing). WHAT AM DOING WRONG? HOW DO I GET THE FAN TO WORK OFF ONE SWITCH AND THE FAN TO THE OTHER SWITCH?

You have an extra wire somewhere.

You should have a white and a black that have constant power.

If you ran two romex cables, you might have a black and a white to fan and light respectively. That accounts for 3 pairs.

Alternatively, you could have a black and white for hot always and cable 14-3 with red/black and white for the fan and light.

I guess the 4th set goes to the vanity in which case your OK.

Where did the 4 cables come from?