screen not rotating on iPad mini

Having checked the settings and screen rotation lock settings there and also the correct function of the side-switch on my new ipad mini it still fails to rotate when needed and yet at other times and in other Apps eg "Weather" it does rotate to the correct defualt orientation. At start-up the"apple" is correct with the cam at the top in portrait orientation - yet as soon as it boots to main screen it rotates 180 and fails to rotate after that. Nothing seems to be capable or landscape mode include Pages etc. Oh and having checked other posts I have tried the reduced accelleration setting too - no joy.