2005 745li battery dead and won't jump or take a charge.

I was recently out of town for 5 weeks and I did not think to put the car on a trickle charge. Anyway when I went to start it the battery was too weak to turn the engine over. I've tried to jump the car with a battery box and nothing. I've also tried to hook the trickle charger up and it's reading "trouble" on the charger instead of "charging". I know the trickle charger is ok because I had to use it on my ML350 also and it charged it great. I'm hoping that someone can tell me the best way to get this car running. Thanks and I'm sorry for the newbie question but this car was just purchased late last summer and this is the first issue. Thanks.

You can try to jump start it (jumper cables) using the terminals under the hood. Those smaller battery chargers do not put out enough amperage to start it. You should also consider battery replacement depending on old it is and if it will hold a charge once you get it started