1: The Airturn must be set to the default iPad Profile. (this means it sends up and down arrows). See the manual regarding how to set the Airturn to a profile. 

2: The Airturn must be paired with your iPad.

3: Settings->Network->Airturn Setup should show Airturn support ON. In addition My device is a BT-105 should be chosen if available IF you have a BT-105. Do not choose My device is a PED.
4: Press once in any text field and briefly press the red power button of the BT-105. The onscreen keyboard will appear. This needs to be done once per application session.

The most common problem will be that the Airturn is not in iPad profile mode. You can tell because sometimes the search window will come up with 1,2,3 or 4 - if it's showing numbers the Airturn is not in the default iPad profile mode.

Here is an article on how to debug (check) your Airturn pedal.