I actually gave up trying to get this to work and went with a competitor instead (Cerberus). Even if I were able to get Anti Theft to install, it would still be incompatible with GO SMS's popups (maybe this was keeping it from being installed in the first place?). Cerberus has an online app that allows control over the phone if it were lost, which is really helpful and completely bypasses the need for sending text messages (although it does texts too). I still use avast for anti virus etc., but until Anti Theft gets fixed (or integrated somehow with GO SMS), I will be sticking with competitor.