Audacity won't record cassettes

I am trying to record home made cassettes onto my computer using Audacity. I
have set the connections to Line in, but Audacity records nothing as the tape
plays. I have one end in the headphone jack of the tape player and the other
two in the Line In jacks for my computer.

When I use the same plugs with my camcorder, it records both audio and video
(not using Audacity for this). And when I record with a microphone, that
records also. So it seems my problem is not with my computer.

What do I need to do to get Audacity to record my cassettes?

Thanks