TabbedPage with icon on iOS 7 causes exception

I have following code :

      this.Children.Add (new PanicPage{Title="Panic", Icon="icon_panic" });
      this.Children.Add (new StatusPage{Title="Status", Icon="icon_status" });
      this.Children.Add (new ConfigPage{Title="Config", Icon="icon_config"  });

On iOS emulator and iPad Mini with iOS 8+ it works fine, without any issue.
However, on iPhone 4 (with iOS 7) it throws Exception:

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

How can I fix it on iOS 7 devices?