Amazon in app purchase is not working in production environment. It's always pointing to Sandbox mode.Each time in onSdkAvailable() sandbox mode flag is becoming true.
public void onSdkAvailable(boolean isSandboxMode) {
// Switch RVS URL from test to production
rvsProductionMode = !isSandboxMode;
}
Are you running the live version of your app downloaded from the Appstore? You need to run the live version of your app for in app purchasing to point to the production environment.