the objects in u r application changes dynamically(means 
vertual objects)

Normally browser will neglect the 404 errors for the image, 
css, and js request and these errors may not be visible for 
the user in the browser. Because css and js are not visible 
object in the page and image may be overwritten with alt 
text. But in QEngine during load test it will be reported 
as 404 error. 
To solve this, check the corresponding URL with your 
application whether the file is missing and do the 
corresponding changes.