Aux Input Doesn't Work with Cassette

Hello,
I took my 2006 Impala in for warrenty work.  The Aux Input will not work with my portable cassette.  The dealer said that the input was fine and that the problem is my portable cassette.  They showed me that it worked with an Ipod just fine. 
 
I tried that cassette player with four different cables with no success.  Then I tried another cassette player with the four cables with no success.  Then I tried an MP3 player and it worked.  Both of the cassette players work just fine when connected to headphones.  Does anyone know what is causing this?  Could the ground of the headphone jacks be different?
 
TIA,
Ed M.

If you are able to use the headphones that work for the cassette player in the MP3 to see if they work might answer that.

Golfer,
I've used three different pairs of headphones with my MP3 player and they all work.  That does not seem to be the problem.
Ed M.
 

Sorry my post was little confusing ... what I was trying to say is if the headphones work for the cassette and the same ones work on the MP3 then likely it's not a wiring problem.
 
It may be the output from the cassette headphone jack could be an attenuated output and could have an impedance issue with the adapter being used.

id agree with golfer- you may have to find the specs on the cassettes output jack and the cars input specs. and look at impedance.

I was thinking there might be something different about the wiring or something like that.  Is there an adapter or way of wiring the cord that will work?  If there is an impedednce and/or attenuation difference, can anything be done about this?
Ed M.

Hi EDM. I'm new to this forum, but your question piqued my interest.

I wonder if you've tried a portable CD player in the AUX jack to see if that might work? Just another troubleshooting step.
I tried an old cassette player that I have and using the cord that I use for my mp3 player, it worked just fine.

Jim S.