HOW-TO
Deploy RadControls for WinForms applications using ClickOnce technology

DESCRIPTION
By default, when preparing a ClickOnce distribution of a Windows Forms Application, VS2005 uses its default settings, which assume that all project assemblies that are located in the GAC of the local machine are also available on the remote server. By default, CopyLocal is set to false for assemblies in the GAC, so they are marked as prerequisites in the application manifest (meaning that ClickOnce expects these to already be present in the remote machine's GAC, so the application does not pack them). Needless to say, this is may cause problems if the assemblies are not registered in the remote server's GAC.

SOLUTION
Here are several simple steps on how to deploy a Windows Forms Application using ClickOnce:

1. Go to your project's Properties.
2. Go to the Publish tab.
3. Click the Application Files... button - it will open a list of files that are required by the distribution.
4. There is a small checkbox at the bottom left corner of the opened Application Files form. If it is not checked, tick it to see all files required by the distribution.
5. You will see all the required assemblies (that are registered in the GAC) probably with a publish status of  Prerequisite(Auto) - this means that the installation assumes the assemblies will be available in the target machine's GAC before the installation takes place.
6. Change the Publish Status field of the required assemblies from "Prerequisite" to Include and accept all changes.
7. Republish the project to check that all is OK.