We have seen many instances of AF11 links that will not come up.  Typically the issue is the Duplexors being installed wrong.  In one case, the Duplexers were actually labeled wrong so it was not the user's fault!  

Here is a low band example for a dual pole setup.  High band is exactly the same setup except the numbers are 2-4-4-2 and 4-2-2-4 for high band instead of 1-3-3-1 and 3-1-1-3 like I have shown here in my example.

Here is a single pole setup.