Telerik MVC Extensions deployment problem

I am writing a website which uses Telerik MVC Extensions, and am getting an error on my test server when I get no such error on my development PC.

The error is ...

Web.config(101): error CS0246: The type or namespace name 'Telerik' could not be found (are you missing a using directive or an assembly reference?)

Here is the relevant line from the web.config file ...

<add 开发者_如何学编程namespace="Telerik.Web.Mvc.UI"/>

I have checked the bin folder on my test server and it does contain the Telerik.Web.Mvc.dll file. The test server is 2008R2.

Have I missed something really obvious here?

---

Do you have multiple applications in your website? In other words, do you have multiple web.config and bin folders?