I'm using the current version of JustCode (2010.2.826.2) and I'm getting the same thing in a standard asp.net 4.0 web application. I get this error ('[object] is defined in an assembly that is not referenced') every time I reference any code behind in an aspx or Master page. For example, I use this code for my loading panel (which I believe came right out of your sample code):
src='<%= RadAjaxLoadingPanel.GetWebResourceUrl(Page, "Telerik.Web.UI.Skins.Default.Ajax.loading.gif") %>' style="margin-top:1px;margin-left:-120px;border:0;" />
JustCode gives me this error, and red-lines the reference "Page":
"C#: The type 'System.Web.UI.Page' is defined in an assembly that is not referenced."
I get a lot of those type of errors, and none of them are valid...
I don't know that I have time to build a sample solution, I can't upload the web app I'm working on. It would be nice if it just worked. I can go back to Resharper is necessary, but I'd prefer to use JustCode if you can work out some of these issues...