My css page is not enabled

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ASP.NET

I m using 6 style sheets in my project. Three of my css is called. But two page is not calling. It is not enabled when I check it on Firebug.

In my css page, I called images using below code.

It is correct or not.If anyother reason css page is not enabled

#theme-default .acitem li a {
    background: url(http://localhost:1551/Employee_Payroll/img/dot.png) repeat-x bottom !important;
    border-right:#bfbfc0 1px solid;
    border-bottom:#babbbb 1px solid;
    border-left:#bfbfc0 1px solid;
    border-top:none !important;
    -moz-border-radius: 0px !important;
    -webkit-border-radius: 0px !important;
    border-radius: 0px !important;

}
#theme-default #primary_nav .icon_block, #theme-default .search_btn{
	background:url(http://localhost:1551/Employee_Payroll/img/alpha.png) no-repeat;
}

My html coding
 <div id="primary_nav" class="g_blue">
		 <ul>
			 <li><a href="#" title="Dashboard"><span class="icon_block m_dashboard">Dashboard </span></a></li>
			 <li><a href="#" title="Projects"><span class="icon_block m_projects">Projects </span></a></li>
			 <li><a href="#" title="Events"><span class="icon_block m_events">Events </span></a></li>
			 <li><a href="#" title="Address Book"><span class="icon_block p_book">Address Book </span></a></li>
			 <li><a href="#" title="Media"><span class="icon_block m_media">Media </span></a></li>
			 <li><a href="#" title="Settings"><span class="icon_block m_settings">Settings </span></a></li>
		 </ul>
	 </div>