some problems about how to create my own plugin?

In CS manual, it told us how to create our own plugin. I followed its steps , and used the code to create a plugin, it name is "myplugin" as the manual told me, then i use the new plugin in one of the cs' tutorial —— simple1 (the application i have run successfully before, and the way to use the plugin ,I also followed the manual strickly.) But when i run "simple1" again( which have add the using of the new plugin ) , it told me that I can't load the plugin ,i don't know why?!

the part of the code is followed:

bool Simple::OnInitialize(int /*argc*/, char* /*argv*/ [])
{
if (!csInitializer::RequestPlugins(GetObjectRegistry(),
CS_REQUEST_VFS,
CS_REQUEST_OPENGL3D,
CS_REQUEST_ENGINE,
CS_REQUEST_FONTSERVER,
CS_REQUEST_IMAGELOADER,
CS_REQUEST_LEVELLOADER,
CS_REQUEST_REPORTER,
CS_REQUEST_PLUGIN("crystalspace.mygame.plugin", iMyApi),
CS_REQUEST_REPORTERLISTENER,
CS_REQUEST_END))
return ReportError("Failed to initialize plugins!");

…………
}

bool Simple::SetupModules ()
{
csRef<iMyApi> my = csQueryRegistry<iMyApi> (object_reg);
if (!my) return ReportError("Failed to locate iMyApi!");
my->DoSomething (1, csVector3 (2, 3, 4));
printf ("%d\n", my->GetSomething ());
…………
}

Please help me !! Thank you!!