BugSir009
Thank you for your reply.
I actually figured out what is happening.
I already installed and was using previous version of the extension.
When Drag & Drop the.crx file, Maxthon indeed update the extension. But because it did not ask to update the extension nor give any notification as "Extension Updated" etc., it shows/seems like nothing happening.
Maybe adding a notification window saying what is happening (e.g. Do you want to update the existing ….) or 'Update successful" will helpful to user in terms of not to make same mistake as me.
(MX portable version 7.5.2.5400)
Thank you