forms app device.openuri system exception in ios

Hi,

I want to open a browser in iOS with my app with this line of code:

Device.openUri(new Uri("http://www.google.com"));

but when that line executes I get this error:

Could not initialize an instance of the type 'MonoTouch.Foundation.NSUrl': the native 'initWithString:' method returned nil.
It is possible to ignore this condition by setting MonoTouch.ObjCRuntime.Class.ThrowOnInitFailure to false.