CSS is not applied in run time

using VS2008 I can see (using Design or Split mode) that the changes I make to the CSS file actually take place.
But when debugging the web site or simply choose File -> view in Browser the css seems to not being upload at all
 
The symptoms are:
1. Nothing defined in the css file - is seen in the browser
2. I also use FireFox plugin called JSView - which enables watching JS and CSS files attached to the page you watch. This plugin also does not indicate that there is any CSS file attached
What's the problem?
 
Tx
Jammusi
 
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