Compass don't allow true north

Hi

I have an iPhone 4S running iOS 6.1.3

The Compass app that comes with the OS will  allow me to display a heading in magnetic north but not in true north.  The true north option  is grayed out.  The magnetic heading displayed is accurate.  I have location services turned on and compass calibration turned on too. Compass displays my correct LAT & LON.  Magnetic and true north options working before. I tried powering the phone off and back on several times.

Sometimes Compass allow me to select the true north option, but when i click done the app switches to magnetic north itself.

Anyone have seen this?Tanks a lot.