Need help with antenna wire @ HU

Hi - I have an Aftermarket Headunit - and up till a couple weeks ago, I used an adapter that connected the BMW factory antenna to the back of the headunit. Everything worked great and had everything properly wiredup to turn on the antenna amp.

I ended up breaking the factory BMW connector and tried cutting it off and crimping on a standard motorola plug (to bypass the adapter piece) - but I couldn't get it to work. Is the antenna just a simple co-axial cable? I connected the middle wire to the antenna cable to the motorola tip, and then the shield part was connected to the negative ground on the plug.

What am I doing wrong? Can I replace the end of the antenna cable? I called the dealer and they said that all I could do was buy the entire length and start for the rear antenna and wire it back thru the car....no crimping allowed!

Any help is appreciated...

Thanks,
Will

I guess I can just call up the dealer and ask for the part number listed! Weird that they said I would have to buy the entire cable again!