Have a look on some av forums, they're very susceptible to interference, the booster may be buggering things up. The one I put in would only work randomly. In the end I gave up and bought a wireless one instead and it works a treat! Maplin have got a good range of them.
You need an amp with a DC pass through. I'm surprised you need a booster, if the cable is only going upstairs then you should not need one, I would check your connections first.