Unreal doesnt let me package apk even i ve everything installed

i ve installed unreal 4, visual studio and ADK , it works for a while but suddenly it wont let me export apk anymore
is there a way to fix this? anyone having similar problems

i had this problem, what i did was uninstall the android sdk then use the android dev kit exe that comes with unreal.

Also make sure the toolchain and Android SDK Is configured in the project settings