I would like to add on top of what @Monte Creasor explained.
I have had the same issue and consulted this bug report which basically says that the problem might be caused by com.android.support:appcompat-v7:21.0.3, on of the main dependencies required to use Android’s new Layout capabilities.
Try going back to the v7:20.0.0, this should solve the issue as it did for me and this bug report writer.
Actually all you have to change is in the app build.gradle
the line:
compile 'com.android.support:appcompat-v7:21.0.3'
or whatever later version you have
to
compile 'com.android.support:appcompat-v7:20.0.0'