Preamp not working

Hi all,

I'm having a problem getting my electric guitar to work in Garageband after feeding it through an ART Tube MP Studio Preamp ( http://www.amazon.com/ART-Tube-Studio-Mic-Preamp/dp/B0002E50MC). I'm using a mono 1/4"-1/4" normal guitar cable as input into the preamp and then a 1/4"-1/8" stereo cable to go into the MBP.

When I plug the cable into my guitar directly without the preamp, I get a lot of buzz and noise with a very weak signal from the guitar. Through the preamp, there's just silence even when I strum on the guitar. The guitar is set on max volume and on clean settings. The voltmeter on the preamp shows it's receiving input from the guitar, so the problem is getting from the preamp to the Mac.

Any advice or help would be appreciated... this is kinda frustrating.

Thanks