I ran into a problem with registering a client script resource this week which had me confused for a while.  I had an existing custom control which registered a script resource and worked as expected.  When I created a new custom control (in another assembly) derived from this control however, I kept getting a ‘‘Resource xyz.js could not be found’’.  The line in the base class that registered the script looked like:

ScriptManager.RegisterClientScriptReource(this.Page, this.GetType(), "xyz.js");

The reason this didn’t work when using the derived control was because the 2nd parameter is used by .NET to find the assembly containing the resource, so it (incorrectly) looked in the assembly containing the derived class instead!  The fix is simply to change the line above to explicitly specify the correct type instead:

ScriptManager.RegisterClientScriptResource(this.Page, typeof(MyBaseCustomControl), "xyz.js");

The resource will then be picked up from the correct assembly.