Samsung Galaxy Mega 6.3 not rooted, issue with SuperSU when updating su binary

After I root my Samsung Galaxy Mega 6.3 (GT-i9205), I downloaded SuperSU from [XDA Forums](http://forum.xda-developers.com/showthread.php?t=1538053) . After I open SuperSU, it asks me to update my su binary. > The SU binary needs to be updated. Continue? But after a long time, it got stuck on > Installing, please wait. If you see this message for more than five minutes please restart and try again. Then I tried to check whether my phone is rooted or not by using a root checker. At last, the answer is *does not have proper root*. Please help!