What do you mean by "the icon is in the folder"? Do you mean it's in the same folder as your pages? In that case, try changing the link to read
without the leading /
The disadvantage of this advice is that if he is using dynamic pages with PHP includes (or other repeatable context), the directories you are linking to may not have the actual icon in it.
It's best to place the icon in the root directory for this reason, and simply identify it via /favicon.ico.