page not found -modules/coolfilter/coolplayer.css

I get the log errors below

page not found modules/coolfilter/coolplayer.css

while the coolplayer.css is exist on the /modules/coolfilter/coolplayer.css
but non core modules including coolfilter.module not on top drupal directory [drupal/modules/coolfilter]
but on [drupal/sites/all/modules/coolfilter

does it mean coolfilter.module only should be installed to and work on the core modules directory?? could it be adjust to multisite settings standards as other non core modules are?

thanks