...for my own information. In Visual Studio 2005, when building custom controls inline with your ASPX page (in the same project), you have to specify “__code” as the Assembly name. The Namespace is still what you have set for your class, however the assembly will be built using a namespace of “app_code” and ASP.Net uses “__code” to refer to it.
If you don't do the above you get a similar error to below:
Could not load file or assembly "AssemblyName" or one of its dependencies. The system cannot find the file specified.