Hopefully you when you say you used regular tile adhesive, you're talking about a good quality thinset(powder that has to be mixed with water) as opposed to premixed mastic.
The brick is very thirsty and will absorb the water out of the thinset too fast causing it not to cure properly. It's always a good idea to spray the bricks with water prior to applying the thinset.
If you go to tileyourworld.com those guys there know everything there is to know about tile.
I think it's better if you ask the question before you do the project.