MAVSDK: NDK_ROOT is undefined

I am using the DroneCodeSDK . But when I try to build for the android , I hit this command sudo make android instal but I get this error Makefile:152: *** NDK_ROOT is undefined, please point the environment variable to android-ndk root.. Stop. Although I have set the NDK_ROOT in .bashrc. Also i have set NDK_ROOT from command prompt . I am using Ubuntu. I am not able to build the code for android. Please suggest how to get rid of this error.