Why does my twitter code not work? - iOS

 float startTime;
 startTime = Time.timeSinceLevelLoad;
 Application.OpenURL ("twitter:///user?screen_name=PlusIntStudios");
     if(Time.timeSinceLevelLoad - startTime <= 1f)    
         Application.OpenURL("https://twitter.com/PlusIntStudios");

This code opens Twitter to the correct place, but then it swaps to Safari and opens the twitter webpage. I am using the exact same code for Facebook and that works fine, so whats the deal with my Twitter code not working?