It appears like you've got at least three different machines plus the cables and jacks in between each which could be causing the issue.

Verify that the turntable is connected correctly and transmitting to the receiver. You should be able to determine that part simply by listening to the music on the receiver's speakers. Once that's done, then verify that the receiver is connected correctly and transmitting out...If you've got another computer with a sound card,,try that one just to make sure that sound is being transmitted from the receiver, through the cables and jacks. If that's working correctly, continue on till you are able to determine the correct problem child.

Hope this helps.