Light switch problem... can you help

When you have two light switches in the same room, controlling the same light... What do I have to do when changing the light switches? I'm changing the standard light switches to the dimmer switches.
So far, I put the dimmer switches on and the lights wouldn't work, they only flickered. Then when I put on the original, standard light switches on again, I could only use one light switch at a time... if I turn the light on by light switch "A" I have to turn it off by "A" ... I can't turn the light on by "A" and turn it off by "B" - I used to be able to before I changed them.
Any idea why this is?

It's still just one circuit.Called 'three way switches".
The original worked thusly:
The first switch directed power to one or the other of two wires to the second switch.
The second switch connected one or the other of those two wires to the light.
If you draw it, you will see that throwing either switch will change the state of the circuit
from 'Off' to 'on' or vice versa.
If it doesn't work now, you've not reconnected it properly.
Check out Fig. 2 here:
http://www.google.com/search?hl=en&sclie…
You need only one dimmer.
If you bought a 'three way' dimmer set there will be a dimmer inserted
between the second switch and the light.
If you bought two dimmers, it wont work.