You have air in that line. If you don't get it out the car won't stop as the air will compress instead of the fluid.

You need to bleed the air out the line. Use the bleeder on top of the caliper to do it.

Best to use a helper:
1) Loosen the bleeder.
2) Press the pedal to about 1" from the floor (almost full travel)....HOLD there.
3) Tighten bleeder.
4) Release pedal.
5) Repeat until no air bubbles come out or you have the desired firmness in your pedal.

To test: press the pedal with the bleeder tight and judge the pedal firmness.

Current Audi Count ---> 5


Previous Audi Count ---> 7

In spite of dealers; I still love Audi :-)