The instruction says to connect (black wire from fan is motor; blue is light):

BLACK wire of one switch to BLACK wire of the fan
BLACK wire of another switch to the BLUE wire of the light
WHITE to WHITE
GREEN to GREEN

I don't have two black wires in the ceiling but only ONE. I also have a red wire. The instruction does not mention red wire at all. Thus, I connected:

BLACK wire of ceiling to BLUE wire of light
RED wire of ceiling to BLACK wire of fan
WHITE to WHITE
GREEN to GREEN

I did exactly the same figuration to the two ceiling fans, yet one of them is not working. I switched connecting back and forth several times:

The fan is working but not the light, when I used the connection mentioned above (The right switch of the double switch works for the fan).

The light is working but not the fan, when I used the connection below (The right switch of the double switch works for the light. It seems to me that only the right switch is working but not the left switch):

BLACK wire of ceiling to BLACK wire of fan
RED wire of ceiling to BLUE wire of light

Anyway, it does not matter which connection I did, there is only ONE working, either the fan or the light, but never both.

In conclusion, it seems to me that the RED wire is working, either connecting to the BLACK or BLUE wires of the fan/light, but never the BLACK wire. The right switch of the double switch box is working but never the left. Sometimes I could hear the left switch hum for 2 seconds and then completely silent without ever working. I forgot which wire was it when i heard the humming.

Please help to determine what's wrong?

Thanks