FYI - for vanilla 2.1 - looks like &$Sender in your plugin is not only deprecated
but will prevent you from getting into the dashboard settings for that plugin.
I assume this was enforced in Vanilla 2.1, because it is not necessary to use &$Sender as an argument and to just simply use $Sender in php5.
so if you wonder why your plugin doesn't work this is the first thing to change.
I may not provide the completed solution you might desire, but I do try to provide honest suggestions to help you solve your issue.