voice chat

hi I recently acquired a pink/green plug in trust HS-1170 headset, but when i try to use it in-world, a green light is on my name in chat box, but not the green activation thing above my avis head. I am trying voice in appropriate areas, but although I can hear others, it seems I have no mic out and therefore unable to speak. Do i have to tell comp to recognise headset, or install it beforehand? I had no prompt to do so when i plugged it in.
It's the same with music - although my edit prefs audios are set to hear streaming music and volumes/masters are up, I rarely hear anything anywhere I go. I must be pushing the wrong buttons or doing something wrong here, but for the life of me I don't know what. Any advice appreciated.
thanks

someone mentioned not long ago that if you are using a usb mic you would probably have to install it before you start sl.

A few of my female friends in sl seem to suffer from blue/green colour blindness, and when they have plugged the green plug into the correct socket the headset has worked correctly.

Pep (Please don't shout at me like they did before they found out I was right)

It probably would be best to restart your computer, with the headset installed, then the system will recognize you're using it. When you start SL, you may need to take a look at the voice chat tab in preferences, and make sure SL notices you've got the headset installed.

(at least...that's what I've had to do, when I had a new headset...)

the pink thing goes in the pink hole.... thats the secret.

also some headsets have an on/off switch for the mic.. make sure thats on.. oh and your audio settings in your PC control panel.. check that out too

oh the pink thing goes in the pink thing huh lol
that's where i have been going wrong all this time - seriously tho'
thanks for that folks, will try out suggestions when i get a bit of
piece and quiet from guitar hero *sighes

Dog, you have to check the whole audio chain.

1. Headset. Mic switched on? Volume level not set to zero? All the plugs in the right holes? If there's a mic Mute switch, make sure it's not on.
2. Windows audio settings. Correct drivers selected for audio input and output? Mic enabled in audio mixer? Volume levels set correctly? (Check that your mic works in some other application besides SL, or use the Windows setup wizard to test it.)
3. SL Voice chat setup correctly? Did you pick the same drivers as you did in Step 2? Have you selected a key to be your microphone push to talk button? (I use the End key myself, it's not used for much of anything else). Do you get green bars in the SL voice chat setup wizard when you speak into your mic?
4. Are you on voice enabled land? If you are, when you first log on or tp in, the chat will say "Connected to Voice Chat". You'll see a white dot over your head. If your mic is set up right, when you hold your mic key and talk, the dot will emit green "radio waves".

I could not get the headset mic to work on an iMac until I went to voice preferences and opened Hardware Options. There was a check box to enable the headset and it has worked fine ever since.

feedback
thanks to all respodees and mainly maureen's and lindal's advice, I got it sorted ty -
as suggested I needed to start pc with headset in, then it seemed to work fine once all settings tweaked thereafter.

yay! Glad you got it all sorted out.