我的搜索框里的按钮的图片不显示是怎么回事啊

@charset"utf-8";

*{
	margin:0;
	padding:0;
	font-size:12px;
}
body{
	background-color:#f5f5f5;
}
.top{
	width:100%;
	height:27px;
	background:url(../images/top_bg.jpg)repeat-x;
}
.top_content{
	width:1000px;
	margin:0 auto;
}
.top_content li{
	list-style-image:url(../images/li_bg.gif);
	float:right;
	width:70px;
	line-height:27px;
}
.top_content a:link,.top_content a:visited{
	color:#8e8e8e;
	text-decoration:none;
}
.top_content a:hover,.top_content a:active{
	color:#900;
	text-decoration:none;
}
.wrap{
	width:1000px;
	margin:0 auto;
}
.logo{
	height:80px;
	background-color:#fff;
}
.logo_left{
	width:200px;
	float:left;
}
.logo_right{
	width:300px;
	float:right;
	height:28px;
	margin-top:30px;
	color:#8e8e8e;
}
.logo_right img{
	vertical-align:middle;
	margin-right:10px;
}
.tel{
	font-size:16px;
	font-family:"微软雅黑";
	color:#c00;
}
.nav{
	height:40px;
}
.nav_left{
	width:10px;
	background:url(../images/nav_left.jpg) no-repeat;
	float:left;
	height:40px;
}
.nav_mid{
	width:980px;
	background:url(../images/nav_bg.jpg) repeat-x;
	float:left;
	height:40px;
}
.nav_left{
	clear:both;
}
.nav_right{
	width:10px;
	background:url(../images/nav_right.jpg) no-repeat;
	float:left;
	height:40px;
}
.nav_mid_left,.nav_mid_right{
	float:left;
}
.nav_mid_left{
	width:680px;
}
.nav_mid_right{
	width:300px;
}
.nav_mid_left li{
	float:left;
	list-style-type:none;
	width:100px;
	text-align:center;
	line-height:40px;
}
.nav_mid_left a:link,.nav_mid_left a:visited{
	text-decoration:none;
	color:#fff;
	font-size:16px;
	font-family:"微软雅黑";
}
.nav_mid_left a:hover,.nav_mid_left a:active{
	text-decoration:none;
	color:#ff0;
	font-size:16px;
	font-family:"微软雅黑";
}
.search_text{
	width:190px;
	height:25px;
	margin-top:6px;
	background:url(../images/search.jpg) no-repeat right center;
	background:#fff;
	padding-right:27px;
	border:1px solid #fff;
}
.main{
	height:250px;
	margin-top:3px;
}
.news{
	width:340px;
	border:1px solid #e8e8e8;
}
.course{
	width:410px;
	border:1px solid #e8e8e8;
	margin:0 7px;
}
.sidebar{
	width:230px;
}
.news,.course,.sidebar{
	height:250px;
	float:left;
}
.title{
	height:35px;
	border-bottom:2px solid #e8e8e8;
}
.title_left{
	width:70%;
	font-family:"微软雅黑";
	font-size:14px;
	font-weight:block;
	color:#786f66;
	float:left;
	line-height:35px;
	padding-left:20px;
}
.title_right{
	width:20%;
	float:right;
	line-height:35px;
	text-align:right;
	padding-right:10px;
}
.title_right a{
	text-decoration:none;
	color:#999999;
}
.pic_news{
	height:80px;
	margin-top:10px;
	line-height:22px;
}
.pic_news img,.course_pic img{
	float:left;
	margin:0 5px;
}
.pic_news a,.course_pic a{
	color:#c00;
	text-decoration:none;
}
.news_list{
	margin-top:20px;
}
.news_list li{
	list-style-type:none;
	background:url(../images/list.jpg)no-repeat;
	padding-left:10px;
	margin:8px;
}
.news_list a:link, .news_list a:visited{
	text-decoration:none;
	color:#000;
}
.news_list a:hover, .news_list a:active{
	text-decoration:none;
	color:#f00;
}
.news_list span{
	color:#999;
	float:right;
}
.course_pic{
	height:120px;
	padding-top:10px;
	line-height:22px;
}
.course_type{
	height:37px;
	width:372px;
	background:url(..images/product_type_bg.jpg)no-repeat;
	margin:20px auto;
}
.course_type li{
	list-style-type:none;
	float:left;
	line-height:37px;
	padding:0 10px;
}
.video{
	height:185px;
	border:1px solid #e8e8e8;
}
.video_content{
	height:150px;
}
.sidebar_ad{
	height:55px;
	border:1px solid #e8e8e8;
	margin-top:10px;
}
.copyright{
	width:100%;
	height:200px;
	background-color:#e8e8e8;
	margin-top:10px;
}
.copyright_content{
	width:1000px;
	margin:0 auto;
	padding-top:20px;
}
.copyright_content li{
	list-style-type:none;
	float:left;
	width:200px;
	background:url(../images/line.png) no-repeat right center;
	text-align:center;
	line-height:30px;
	font-family:"微软雅黑";
}
.copyright_content a{
	text-decoration:none;
	color:#999;
	font-size:18px;
}
.copyright_content li ul li a{
	font-size:14px;
}