I'm just in the brotherhood, standing in the kitchen at the back door where to let his companions. If I make the door to be my companion just stand there and do not follow me is probably a bug or do I have to activate what so come along?

Have an older game was loaded where I have the same problem

Have just seen that it already is a thread for this problem. I do not have a save point before I enter UB

Sorry for my bad english (german - english translator)

Restart level?

Restarting the level worked for me, once. Then I wanted to do something slightly different, and now I can't get it working again.

Meh.

Is the next level soloable?

I ran into the same problem and didn't realize it was not a solo mission until the final fight which was quite challenging. I'm a shaman and playing on hard but I had a spirit to help me out. If I remember right its three rooms first room has two enemies, second has two and third has four but with some twists but I managed to beat it first time. Still had to pay those lazy runners that didn't do anything at all.

Am I wrong or can the main character not die?

Oh, he/she can definitely die, as I found out when stepping in front of a sentry gun without the correct key card.

Anyways, I managed to get my team to follow me. Seems the new *save-anywhere* feature that came with the expansion, can cause some bugs in the original campaign. For anyone having trouble with this, restart the level, and neither save nor quicksave before you get your team inside. That's what finally solved it for me.

Borkis is right. This bug was driving me crazy, couldn't get my team to follow me no matter how many times I reloaded the level. Basically if you save even once they will not follow you.
Terrible bug, nearly gave up on the game. Thanks so much.

Thanks for the help, have the level was restarted and can now continue playing without any problems.