Plugin Not get fired in Send Email Ribbon Button CRM 2011

Hi,

I have created a plugin which i need to fire during send email ribbon button  clicked . But the plugin is not getting fired.

Even if i debug the plugin , i am not able to debug.  after some goggle i go through the bellow link where i am facing same error.

http://stackoverflow.com/questions/15405394/why-send-email-plugin-is-not-working

Profiler> Plug-in AppDomain Created
Profiler> Parsed Profiler File Successfully.
Profiler> Constructor Execution Started: XXXXXXXX
Profiler> Constructor Execution Completed Successfully (Duration = 8ms).
Profiler> Profiler Execution Started: XXXXXXXXXXX
Plug-in> Entered CRMEmailToParticipantsPackage.EmailPlugins.PostParticipantCreate.Execute(), 
Plug-in> Exiting CRMEmailToParticipantsPackage.EmailPlugins.PostParticipantCreate.Execute(),
Profiler> Profiler Execution Completed Successfully (Duration = 45ms).
Profiler> Profiler AppDomain Unloaded

i have registered my plugin in update Step 
 message  : Send
Primary Entity = email

Post operation
and my Image is in post Image = Target

Grateful for any help!!