我的aspx页面里面写了js，想要调用c#里面的一个函数，但是总是出错。请大家帮帮我
JS:
<script>
function opendialog()
{
var someValue=window.showModalDialog ("cate.aspx","","dialogWidth=800px;dialogHeight=800px;status=no;help=no;scrollbars=yes")
PageMethods.BindToDropList();
}
</script>
aspx:
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true"> </asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:DropDownList Style="z-index: 0" ID="dropCate" runat="server" OnSelectedIndexChanged="dropCate_SelectedIndexChanged" AutoPostBack="True">
</asp:DropDownList>
<asp:DropDownList Style="z-index: 0" ID="dropCate1" runat="server">
</asp:DropDownList>
</ContentTemplate>
</asp:UpdatePanel>
</td>
<td align="left">
<input id="Button1" type="button" value="全部招聘岗位" onclick="opendialog()" />
</td>
c#：
private void BindToDropList()
{
string strConn = ConfigurationSettings.AppSettings["connectionstring"];
SqlConnection con=new SqlConnection(strConn);
String strSQL="select * from Company_Post_Sort";
SqlCommand cmdCate = new SqlCommand(strSQL, con);
con.Open();
SqlDataReader dtr = cmdCate.ExecuteReader();
this.dropCate.DataSource = dtr;
this.dropCate.DataTextField = "sort";
this.dropCate.DataValueField = "id";
this.dropCate.DataBind();
dropCate.Items.Insert(0, new ListItem("----请选择---", "0"));
dropCate.SelectedIndex = 1;
dtr.Close();
string strClass = "select * from Company_Post where sort_id = " +this.dropCate.SelectedValue;
SqlCommand cmdClass = new SqlCommand(strClass, con);
dtr = cmdClass.ExecuteReader();
this.dropCate1.DataSource = dtr;
this.dropCate1.DataTextField = "post";
this.dropCate1.DataValueField = "id";
this.dropCate1.DataBind();
dropCate1.Items.Insert(0, new ListItem("----请选择---", "0"));
dropCate1.SelectedIndex = 1;
dtr.Close();
con.Close();
}
------解决方案--------------------------------------------------------
把C# code 写道webservice中，ajax调用
可以用jQuery ajax 简单
也可以用微软自己的机制，scriptmanager
不懂就去网上搜相关知识就可以了