遍历取RadioButtonList值的问题

Question

前后代码<asp:GridView ID="gvAnserCard" runat="server" AutoGenerateColumns="false" SkinID="print">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<table style="width:100%;">
    <tr>
    <td style="height: 18px">
        第<asp:Label ID="labNum" runat="server" Text='<%# Eval("AnswerID") %>'></asp:Label>题</td>
    </tr>
    <tr>        
    <td>
        <asp:RadioButtonList ID="rbtnList" runat="server" RepeatDirection="Horizontal">
            <asp:ListItem>A</asp:ListItem>
            <asp:ListItem>B</asp:ListItem>
            <asp:ListItem>C</asp:ListItem>
            <asp:ListItem>D</asp:ListItem>
        </asp:RadioButtonList>
    </td>
    </tr>
    </table>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>后台我用foreach遍历的时候.
 foreach (GridViewRow gRow in gvAnserCard.Rows)
                {
                    Label labNum = (Label)gRow.FindControl("labNum");
                    RadioButtonList rbtnList = (RadioButtonList)gRow.FindControl("rbtnList");
                    
                    cm.Parameters["@AnswerID"].Value = labNum.Text;                   
                    cm.Parameters["@UserAnswer"].Value = rbtnList.SelectedItem.Value;
}
怎么我数据库写进去的UserAnswer是空值...

Answer 1

rbtnList.SelectedValue
foreach(ListItem   item   in   rbtnList.Items)
{    } 

Answer 2

  cm.Parameters["@UserAnswer"].Value = rbtnList.SelectedValue;