EZ Page Image click to load larger image

[J9MM0]

Hi All,
I have this code on one of my EZ page:

<a href="#" onclick="function onclick(event) {function onclick(event) {MyWindow=window.open('/images/Build Costs 2013.png','MyWindow','toolbar=no,location=no,directories=no,status=no, menubar=no,scrollbars=yes,width=1400,height=800'); return false;
}}"><img src="/images/Build Costs 2013 small.png" /><br />Please click the table for a larger view.</a>

It loads an image and if you click it it's supposed to load a larger image.
On my previous site it worked fine but on this new website when you click the image instead of loading a larger image it takes you back to the index page.
I was hoping someone can advise as to whats wrong with the code.
Thanks.