Just to be clear on your connections:
You have the red/white audio cables connected from the TV
audio out to one of the analog
inputs (such as Video 1) on the receiver? If so, that is the correct connection.
I still have a 32" Toshiba CRT and it has one set of audio outs and they are fixed output and always active; however I have seen some models that have a menu option to change the audio outs from fixed to variable and still others (like my sister's 43" Toshiba) have two sets of audio outputs - one marked 'fixed' and the other marked 'variable'.
If your connections are right and you get no sound then I would suspect that the tv audio out is 'variable' and the tv volume is turned way down. If you turn up the tv volume and then hear sound the audio out is variable. In case you aren't aware 'variable' means that the output varies with the volume control of the tv. If you have the manual for the TV, it will say something like 'fixed output: 350 mV; variable output: 0 - 350 mV', so you can see that if the output is variable and the tv volume is all the way down the signal level will be 0 mV (and zero is silence.
)
You want to use fixed output if possible so that the tv volume control has no affect. No Toshiba TV I've ever owned or seen has required you to turn the internal speakers off to make the audio outs active, but other TVs do so also check if there is a menu setting to turn off the internal speakers.