Extend an Appcelerator app with native iOS8 widgets

Hi, I have some problems running a today widget on my iPhone. I followed this guide and used the latest xCode and Appcelerator Titanium release with the 4.0.0.RC4 SDK.

http://docs.appcelerator.com/platform/latest/#!/guide/Integrate_a_Native_iOS_App_Extension_or_WatchKit_App

When I run my native extension on the iPhone Simulator it works perfectly. I included the extension in my tiapp.xml like this:

<extensions>
    <extension projectPath="/Users/foddy/Developer/Titanium Workspace/Extentions/myappname/">NewMails</extension>
</extensions>

But when I try to test the app on the iPhone I just get the notice that a new extension is available on my notification center and I can choose my extension with the '+' button. But nothing appears?! It works on the Simulator but not on my iPhone with iOS 8.3. Has somebody the same problem with Today widgets on the iPhone?