ToolTip为何无法显示？

小弟在用DataGrid绑定的ImageButton上使用了ToolTip属性：
<asp:ImageButton ID="DeleteSelectedCourse" ImageUrl="../../images/delete.gif"  OnCommand="DeleteSelectedCourse_Click" CommandArgument='<%# DataBinder.Eval(Container, "DataItem.Select_ID")%>' runat="server" ToolTip="撤销该课程"/>
然而在运行时却发现提示显示不出来，是怎么回事？注明一下，如果是Button控件，则完全正常，什么原因？

解决方案 »

  1.   

    <html xmlns="http://www.w3.org/1999/xhtml" >
     <head id="Head1"><link rel="stylesheet" rev="stylesheet" href="../../css/list.css" type="text/css" media="all" />
     <style type="text/css">
    <!--
    .infotitle {
    font-size: 14px;
    font-weight: bold;
    color: #000000;
    }
    .STYLE1 {font-size: 14px; font-weight: bold; color: #4C4C4C; }
    .STYLE2 {color: #4C4C4C; font-size: 12px;}
    .STYLE3 {color: #4C4C4C; font-weight: bold; font-size: 13px;}
    body {
    margin-top: 0px;
    margin-bottom: 0px;
    }
    -->
     </style>
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title></title></head>
    <body oncontextmenu=self.event.returnValue=false>
        <form name="form1" method="post" action="ViewSelectedCourse.aspx" id="form1">
    <div>
    <input type="hidden" name="__EVENTTARGET" id="__EVENTTARGET" value="" />
    <input type="hidden" name="__EVENTARGUMENT" id="__EVENTARGUMENT" value="" />
    <input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="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" />
    </div><script type="text/javascript">
    <!--
    var theForm = document.forms['form1'];
    if (!theForm) {
        theForm = document.form1;
    }
    function __doPostBack(eventTarget, eventArgument) {
        if (!theForm.onsubmit || (theForm.onsubmit() != false)) {
            theForm.__EVENTTARGET.value = eventTarget;
            theForm.__EVENTARGUMENT.value = eventArgument;
            theForm.submit();
        }
    }
    // -->
    </script>
        <table align=center>
        <tr>
        <td style="width: 631px" valign="top"><table cellspacing="0" border="0" id="SelectedCourseList" style="border-collapse:collapse;">
    <tr>
    <td>
                        <table width="631" bgcolor="#EAEAEA" border="1" cellspacing="0"  class="STYLE2">
                    </td>
    </tr><tr>
    <td>
                        <tr>
                            <td width="60" align="center"><a id="SelectedCourseList_ctl03_Course_ID" href="javascript:__doPostBack('SelectedCourseList$ctl03$Course_ID','')">C0001</a></td>
                            <td width="160">&nbsp;&nbsp;<span id="SelectedCourseList_ctl03_Course_Name">数学分析</span></td>
                            <td width="60" align="center"><a id="SelectedCourseList_ctl03_TeachClass_ID" href="javascript:__doPostBack('SelectedCourseList$ctl03$TeachClass_ID','')">0001</a></td>
                            <td width="68">&nbsp;&nbsp;<span id="SelectedCourseList_ctl03_Teacher_Name">苏化明</span></td>
                            <td width="32" align="center"><span id="SelectedCourseList_ctl03_Credit">3</span></td>
                            <td width="82">&nbsp;&nbsp;<span id="SelectedCourseList_ctl03_CourseType_Name">专业必修课</span></td>
                            <td width="36" align="center"><input type="image" name="SelectedCourseList$ctl03$DeleteSelectedCourse" id="SelectedCourseList_ctl03_DeleteSelectedCourse" title="撤销该课程" src="../../images/delete.gif" onclick="return confirm('是否撤销所选择的课程？');" style="border-width:0px;" />
                            
                        </tr>
                    </td>
    </tr><tr>
    <td>
                        <tr>
                            <td></td>
                            <td></td>
                            <td></td>
                            <td></td>
                            <td></td>
                            <td align="center">学分总计：</td>
                            <td align="center"><span id="SelectedCourseList_ctl04_TotalCredit">3</span>
                            </td>
                        </tr>                      
                        </table>
                    </td>
    </tr><tr>
    <td><span>1</span></td>
    </tr>
    </table>
    </td>
        </tr>
        </table>
        </form>
    </body>
    </html>这个是html原文件
      

  2.   

    看来这个问题不是我一个人遇到啊，没有人知道么？CSDN上的高手不要让我失望啊！
      

  3.   

    runat="server" 是在服务器上执行,当然就出不了提示了
      

  4.   

    楼上帮帮我啊，那我该怎么用？
    为什么Button控件就没有这个问题，他也有runat="server" 属性阿