Trim的问题(50分求解)

<%@ Page Language="C#" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"><script runat="server">
void Page_Load(object sender,EventArgs e)
{
    char[] charDel ={':','-',' '};
    string strNow = DateTime.Now.ToString();
    string strNewName = strNow.TrimStart(charDel);
    Response.Write(strNow + "<br>" + strNewName);
}
</script><html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    
    </div>
    </form>
</body>
</html>我想用trim中删除字符功能把DateTime.Now中的“';','-'”和空格去掉
怎么不行的？？