replacing Nav Menu items with images... cont'd

@Michelle Shull this was not an issue with order of css overrides. maybe another Dev has an idea?
Theme: Suffusion

Hey Dev team! I'm having trouble solving this issue.

I recently made a post and the solution you guys gave me worked perfect. I tried to duplicate it for my other site and it didn't work :disappointed:

I am trying to swap Nav Menu items for images. Here is the code I tried:

#menu-item-29 a:highlighted, #menu-item-29 a:visited, #menu-item-29 a {
background:url('') no-repeat center 0 !important;
background-color:black !important;

#menu-item-29 a:hover {
background-color:grey !important;

For whatever reason, its not working this time despite changing the menu item numbers. I have duplicated it once already and it worked fine, but I can't get it to work on this site. Any ideas?