2 things here, are you trying to set an AP up as a client bridge (example: connecting a LAN printer to an AP) or are you trying to establish a wireless bridge between 2 APs/locations (Meshconnex)?
If it's the latter, attached instructions should help.
IMPORTANT: if testing in the lab, make sure:
1 - The APs are a few feet apart
2 - The Radio power is reduced to 1 (increase before deploying)
I hope this helps