Thank you for you patience lupold.

I've controlled and supportedFeatures is not null for any of the entries in DesktopModules table.

But I have another question: the problem could be the name of the controller class? When I created the module using the module template, DotNetNuke created a controller class named YourCompany.Modules.LeoModule.LeoModuleController. I've renamed it in DotNetNuke.Modules.LeoModule.LeoController. I've also renamed it in Host->Module definitions->Controller class. Do I have to put the correct name in other files? Beacuse I've seen that in the row in which I've the error (278 of Reflection.vb) the TypeName has a value which does not correspond to the correct name of the controller class.

Sorry, I didn't know the namespace DotnetNuke is reserved to core module (when I created the module I used the adefwebserver tutorial, but it doesn't tell about the namespaces...). Now I've changed the namespace, as you have told me, but the research functionality keeps on working badly.