Charger Iphone Adaptor

I used to have a Monster® iCarPlay™ FM transmitter plus charger and it worked great!!! But then i got a 4th gen Nano and it won't charge. i could deal with that but now the thing only plays music out of one of my 4 speakers.....so i bought a new one from radio shack. a Monster® iCarPlay™ 800 Transmitter for iPod® and iPhone™, which even charges my new Nano and my friends iphone (yay!). But this thing really sucks.....no matter what station i put it on i get static and that NEVER happened with the old one. Basically i wanna know why the old one works but the new one doesnt and what should i do (return the new one? try a cassette one instead of a transmitter? is there some way to make this new one work? etc.)