title: Xcode Beta 6.2 does not start App Watch extension
body: <p>My watchkit app can't run on simulator. </p>
  
  <p>After I choose the xxx Watch App scheme, and click Run,</p>
  
  <p>It display "Running xxx on iPhone 6", but never go to the second step of 
  "Running xxx WatchKit Extension", so Watch application never displayed.</p>
  
  <p>I following Apple's standard steps of creating a simple demo application. Apple's demo app can't be started either. Anything I did wrong?</p>