Sound problem with Skype.

Hi.

I have installed Ubuntu 7.04, Feisty Fawn.

I also have installed Skype 1.3.0.53_API.

I can hear the Skype testcenter, and I can hear myself speaking in the 
michrophone.
But I cannot hear myself when the link changes, and where I should hear 
myself from the Skype testcenter.

I use the onboard AC97 sound card, and it is also selcted when I look 
into the tools>option>sound devices.

If I selecet System>Preferences>sound, all the tests are being ok.

What could be the reason for the culprit ?