I Installed a Add on Livery for the PMDG B-737 Ngxu BBJ  (file "texture.n.737.m")  (the livery was installed using PMDG's Operations Center)  Wheni loaded P3DV4, and the B-737 all of the instrument displays were blank and none of the controls worked, including all the switches etc.  I loaded the B-747 and got the same result,  However the B-777 works fine.  I uninstalled and deleted all files related to the B-737 and B-747 on my C & E drives and did a complete reinstall, same result.

I have left two posts on PMDG's Support form and so far no help or reply.

I would appreciate any help someone can give me,  I am not a computer guru so please keep instructions simple (SORRY)

Thanks any help in appreciated.

Ken Hand

Sounds like a license issue. You need to own a ticket with PMDG and they can help you sort it out. A similar thing happened to me recently so this is where my suggestion comes from. 
 

-Braun

Try installing simconnect from your P3D Folder\redist\Interface\FSX-SP2-XPACK\retail\lib