__doPostBack is not triggering click event handler

Hello,

I have a method:

Button1_Click(sender) {
   if (something)
       __doPostBack(sender.id, "Click");
}

sender does get the correct reference to the button, and the sender.id property is valid, and "something" is a valid expression.  __doPostBack does post back ot the server, but the button referenced does not have it's click event handler called.  Why is that?  I see for other people this works.
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