I have two Android phones, one is 4.2.1 and the other is 2.3.1. I can debug on both with no problem. But when I create a package and install it manually, the app crashes on the 2.3.1 phone. It crashes no matter if the Mono libraries are installed or not. I have set the Target Framework in the Project's Options to Android 2.3 (Gingerbread). I also tried a fully signed and published version. The app installs fine but when you try to start it, it crashes immediately. The Gingerbread version does work fine on the 4.2.1 phone though. I have installed and executed successfully a similar app on the 2.3.1 phone using Eclipse. Any ideas what I'm doing wrong or am I missing a step or two?