ImageButton Code-behind

I have a form with an ImageButton and I have assigned a PostBackUrl to the ImageButton.  I would like to execute some code when the image button is clicked as well.  I thought that simply adding an ImageButton1_Click event would do the trick, but it isn't firing.  I'm not getting any errors and everything else seems to work fine.  Any suggestions on how I can execute some code upon the ImageButton being clicked and still post data to the PostBackUrl I've assigned?
...