ASP.Net Webfor Mobile View

I have a web for application. I want the site to use the same master page for desktop and mobile. When I run my site in regular view, it is fine. But, if I view the site on a mobile device (or emulate a mobile device in my browser) I get this error:

System.Web.HttpException (0x80004005): Could not load type 'com.mysite.p3.myapplication.Site_Mobile'. at System.Web.UI.TemplateParser.GetType(String typeName, Boolean ignoreCase, Boolean throwOnError) at System.Web.UI.TemplateParser.ProcessInheritsAttribute(String baseTypeName, String codeFileBaseTypeName, String src, Assembly assembly)

I have tried editing my RouteConfig.vb file to handle friendly URL, but this causes other issues with my servers Single Sign On. Is there another way to use the same master page for desktop and mobile? I tried adding a view switcher, but the load event never fires.

thanks