Prototype plugins are not loading

Hi,
I installed nginx as reverse proxy in-front of Apache.
Configurations are similar to this tutorial
After setting up, everything works greatly except prototypejs seems stop working.
For example, at create/edit post page, can’t click on “permalink edit” button and I get this javascript error @ line 4619 from prototype.js?ver=1.6.1:

element.dispatchEvent is not a function
[Break On This Error] 	

element.dispatchEvent(event);

Media upload icons are not working as well. If I click on them, upload page is open in new page, not inside the same page with popup.

Thank you so much for helping in advance.