Tina, I need you to show me the frame in which <a class="MenuLink" id="lnkChangePassword" ...> resides. Showing me another frame (“MainFrame”) does not help.
I’m detecting you are unwilling or extremely reserved about posting your site’s HTML. If you have security concerns, don’t post any URLs and blank out any sensitive info. I can’t help you without seeing your code (test code, HTML code, etc.).
Assuming you don’t want to post any more info, the following is the general solution to the problem as it stands right now:
window.frames['your-frame-name-here'].document.querySelector('#lnkChangePassword').click()
Once you have proved that works from the browser console, use WebUI.executeJavaScript to issue your click on that element using that same piece of JavaScript.