Magnetic interference

[Dust Rider]

I keep getting this message, Magnetic interference. I don't know what I have done wrong, I have tried to calibrate Compass again but no luck for me. I looked for help from 3dr forums, and what not but no luck. Please share if anyone knows what the problem is.
Thx

 

[Acroduster]

This error can occur often when on reinforced concrete. Try moving your starting point around.

 

[Dust Rider]

This error can occur often when on reinforced concrete. Try moving your starting point around.

I have tried that as well, still no luck.
I appriciate the quick reply.
Thx

 

[Dust Rider]

I gave the compass calibration a second try, and it worked successfully.
What a relief