Dynamic libraries problem.

Hello. I'm trying to implement a plugin system for an application. The
application has two parts: a core dynamic library and an executable.
The application uses the dynamic library to work. With these two
pieces, I can write plugins (in theory), which are dynamic libraries
(.so, using linux platform) . My plugin uses the core library. The
problem is the following. I have an structure like this:

(Core dynamic library)

File Plugin.hpp

class PluginsManager : public Singleton<PluginsManager {
    PluginsMap plugins_;

    bool registerPlugin(const std::string & plugid, PluginPtr p)
    {
        plugins_[id] = p;
        return true;
    }
};

#define REGISTER_PLUGIN(pluginid, plugintype, ns) \
const static bool registered##ns##plugintype =
PluginsManager::instance().registerPlugin(pluginid, \
PluginPtr(new plugintype))

(My Plugin)

namespace Plugins {

class MyPlugin : public Plugin {
   ....
};

}

REGISTER_PLUGIN("MyPlugin", MyPlugin, Plugins);

(main.cpp)

int main()
{
    //Loads .so plugin files, which in turn execute REGISTER_PLUGIN
macro for each file and SHOULD
    //register plugins
    PluginsManager::instance().init();

    //This won't work. I registered the plugin when loaded the dynamic
library, but it doesn't work at all.
    //The plugin is not in the container
    PluginsManager::instance().getPlugin("MyPlugin")->init();
}

When I try to access the plugin (the dynamic library is CORRECTLY
loaded, and LD_LIBRARY_PATH is correctly set) it seems as if the
instance I am accessing from the main program were different from the
instance in which I register the plugin. Can anyone help? Maybe is a
link or order of initialization problem? Thanks for your time. This is
making me crazy.

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