It seems that this option is disabled for WP8 projects.
More info here: WP8 SDK import Service Reference with task-based operations not possible
Question
When I'm adding a service reference in Visual Studio Express 2012 for Windows Phone I can't choose the option "generate task based operations". I can't even uncheck the Allow generation of asynchronous operations checkbox.
I'm using the following address: http://www.webservicex.com/globalweather.asmx?wsdl
Screenshot: http://snag.gy/sLjrg.jpg
I'm missing something?
Solution
It seems that this option is disabled for WP8 projects.
More info here: WP8 SDK import Service Reference with task-based operations not possible