Issue when calling an application from webApp

I Create a web application that when I click on button this open another application installed on iphone. I call anothe开发者_如何学JAVAr application with this code:

window.launchAPP = function() 
   {
       setTimeout(function() 
       {
           window.location = 'http://www.app.com/'
       }, 500);
       window.location = 'app://';   
   };

This work fine if my webapp is called from safari. If I call webapp from my menu, after "add to home screen", other application is not called and I have this error message: "cannot open app. App could not be opened. the error was the url can't be shown:".

Where is my mistake???

Launching Your Own Application via a Custom URL Scheme

Like in android the best choice is registering your custom URL Scheme.