I have 2 Activities, each in seperate applications. Activity1 has a button the user can click and it calls the second activity using an intent in its onClick()
So here is the final solution that took care of it:
I changed the intent for Activity1 to the following:
Intent myIntent = new Intent();
myIntent.setClassName("com.myProject", "com.myProject.Activity2");
startActivityForResult(myIntent, 600);
For some reason Android requires the fully qualified name for the second parameter in addition to the package name given by the first parameter. Now it works! :)