Well I don't know if I may refer to some other lessons then GT, but I found this 4 part video series on Barre Chords on Youtube solve about every single Barre problem I know off.

Good luck!

Part 1: http://www.youtube.com/watch?v=MpMhueVEz2g&feature=player_embedded
Part 2: http://www.youtube.com/watch?v=FNe4oHE8WLU&feature=player_embedded
Part 3: http://www.youtube.com/watch?v=ioU_ItTzm90&feature=player_embedded
Part 4: http://www.youtube.com/watch?v=w2Xhl7QkXEA&feature=player_embedded

If you still have problems after these lessons, just keep practicing, you'll get there! Finger needs to build up strength, sometimes may take a long time!