I had a similar problem with one of my radios in a particular aircraft.
It was not possible to switch the radios on from any of the panel switches or radio switches, possibly due to an omission by the designer in the "Panel Folder" text file...?
I posted the problem on the Forum and one of the lads came back with the cure....
"Go to Key Assignments and assign Caps + A to switch on the radios, (Avionics)".
Worked fine then...

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Cheers all...

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Paul.
P.S. I've got the Antanov package, and have never been able to cure the strange missing engine gauges, etc...

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...a bit of "iffy" programming...?
LOL...!
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.