title: "R" or "Resource" giving me error in Android Studio
body: <p>My problem is that whenever I add a new activity by its defaults, "R" just can't be recognized and giving me red color.
  The first activity I added was LoginActivity, the ready to use template and no problems with it, and after that any other activity will give me the R error.
  I tried "Clean Project" and "Rebuild" as most solutions say, but didn't correct it.
  Is there something I'm missing?</p>
  
  <p>The error is "cannot resolve symbol R", if you know it.
  Sorry I couldn't upload a pic to make it clear.</p>