Hi AfkMan thanks for your reply.
The freqs I use are set on the "Radio 1 VHF AM":
texaco=150
arcsomething=140
I use the Warthog HOTAS Throttle Mike Switch Forward to call the Tankers
The refueling port is set to "open".
I play on full simulation settings for everything.
I am flying so that the inner tanker engines are "touching" my HUD frame already.
I am not at home right now, but now I remember a thing which I need to check when back in the game:
Before taking off and locating and contacting the tankers, I changed my loadout on the ground using the intercom panel and the HotMike Button pushed. I forgot to set it back. May this cause failing VHF AM communications?
*** EDIT ****
OK, just read WarriorX´s Radio Tutorial. Great Read! Its on the last slide. The Intercom Ground Crew thing most probably caused my problem. Need to set it back to VHF. And push the radio buttons slowly. I am a speed-clicker :-) So I will try this again and hope I can suck up some Jetfuel :-D