Problem: No resource identifier found for attribute 'fontFamily' in package 'android'
Solution:
1. Make sure you have the minSdkVersion set to 16+. fontFamily was added in API Level 16.
2. Check the version of your device. It should be Android version 4.1 or higher.
Resources:
http://developer.android.com/reference/android/R.attr.html#fontFamily
http://stackoverflow.com/questions/14650732/no-resource-identifier-found-for-attribute-fontfamily-in-package-android
