Exit Button Problem

Newbie here. I just completed a HTML course and the exit button doesn't work. My client uploaded it to their Microsoft Application and Network Access Portal (Windows Server 2008 R2). I have a top.window.close() action for the button. it doesn't work though. (When I upload the course to my server on GoDaddy the exit button works). Should I use a different web address--other than top.window.close()--in the Action Properties? Should I remove the onMClkGoTo action and use Exit Title/Close Window? Your thoughts. My first time out. Please reply. Thanks!