How do I search for Digital Systems with the 396XT?

[wv_mountaineer]

How do I search for Digital Systems and or frequencies with the 396XT? Either by doing a direct search / custom search or a limit search. Seems to me I would just do this the same way as I do for an analog search, right? Well, that sounds easy enough however I am not picking anything up? I could see this being the case if I were at home but I am sitting inside the Pittsburgh Children's Hospital right outside of downtown and kind of on top of a hill. I think I should be picking up something digital around this location.
Any thoughts or tips would be appreciated.

 

[DaveIN]

Make sure you have control channel only set in the settings for search.

 

[scanningisfun]

Make sure you have control channel only set in the settings for search.

Or you can just listen for control channels and note them and set up different systems.