Headset not recognized

[treeclimber]

I plugged my headset into my husband's desktop running Karmic. The sound card is working fine ( just listened to music on the external speakers). But when I plug in the headset, I can't hear anything or record. I checked sound preferences and input doesn't show any device. Output only shows the external speakers. I know the headset works because I use it on my Ubuntu laptop and my daughter has used it on her Windows laptop. Is this a problem with the sound card, the OS, or maybe just the jacks for the headset? This computer is still under warranty for hardware, so I need to know. How can I determine what the problem is? Any ideas? Thanks!!

[lyall]

are you plugging the headset in the back of the PC or the front

on the back there should be three ports
one for the headphones or speakers (green)
one for the mic (redish)
one for the line-in (blue)

on the front there should be two ports
one for headphones (green)
one for the mic (redish)

check you connection again to see

good luck and have fun learning

[treeclimber]

They are on the front and yes, I did plug them into the right jacks. One is pink and one is green, just like my headset. This is on a 6 month old Dell laptop.