Please help, remote start won't start, cuts out

It's an Avital 3100 going into a 1990 bmw 325i.

When I try to remote start, it just cranks for a split second, and EVERYTHING cuts out, and doesn't come back on until the avital tries to re-start. 

I turned the key to the run position, and tried rem starting it, and it still just cranks for a split second, and when it does, the dash lights cut out for a split second, which does not happen during regular cranking.

I've tried alot and checked my connections and have no idea, what could be the problem?

Could it be something to do with the factory immobilizer?  The owner never uses it, so i'm assuming it's always off, I'm not familar with the system at all.

Thanks in advance

on a side note...

I have another problem in that I need the ign to be powered for the neutral safety switch to work.  without this grounded on the avital end, the Avital won't even "think about starting".  the brake light sensor does not have to be hooked up for it to "think about starting" so I was thinking of wiring this (with a relay to invert polarity) as the neutral switch, and using another relay on the neutral sensing wire for the brake. But I'll work on that once I get this to start (I've just been grounding the neutral out during this)  Any problems with hooking it up the way i'm thinking?

FIXED!

strange there's nothing about an immobilizer, it mentions it in the factory manual, but i guess you don't have to worry about it...

i gave up late last night, but before i crashed, i checked the voltage, and it  was really low, so i threw the battery on the charger overnight, charged fully.

figured i'd try one more time just for kicks in the morning, to my surprise, fired right up...

I guess that the battery was so low that when the car tried to start there wasn't enough juice to keep the avital alive.

the neutral switch works too.

Thanks for the reply!