Images are there but it says they are not found!

Hi Heros

YSLOW says it can't find the following resources but when you click on the links they are actually there - what could be the problem
There are 53 requests that are 404 Not Found

-> Result of Pagespeed
The following requests are returning 404/410 responses. Either fix the broken links, or remove the references to the non-existent resources.

Kind regards