Christian,
For the SkyRadar, it is best to have the SkyRadar up and running for about a minute or so. Then make sure the iFly 700 is connected to the SkyRadar. Boot the iFly 700 up and enter navigation. You should see the Weather Mode go from Pre-Flight to Live, Live No, Data or Live, Idle.
SkyRadar units sometimes behave a little different depending on their driver and build. Another possible option is to have bot the iFly 700 and the SkyRadar up and running, then connect the two device with the USB cable. If this is not working give our support department a call.
ps- I looked your name up so I could be more formal, hope you don't mind.