I would do a few things to see why it doesn't work. First thing I would
do would be use the "F12 Developer Tools" and use that to see what may be
happening. Sometimes it might be showing that something is being blocked.
This way you can see if it is being fired or not. If you are unable to find
anything useful in that, try resetting your Internet Explorer. You would do
this by selecting internet options, click the advance key, and reset. I
have run into issues where IE was just messed up from me constantly
debugging. I would also check to see if it works on Firefox and Chrome. As
for you code, the image button looks fine. To me, this is going to be a
issue with your actual browser and not your code. You could also try
uninstalling IE 10 and see if it works without compatibility mode in IE 9.