C# – RadioButtonList SelectedItem always returns EmptyString

I have this custom radiobuttonlist I'm using in my .aspx page in order to be able to get the GroupName to actually work since I will have 2 RadiobuttonList controls on the same .aspx page:

public class CustRadioButtonList : RadioButtonList, IRepeatInfoUser
{
    void IRepeatInfoUser.RenderItem(ListItemType itemType, int repeatIndex, RepeatInfo repeatInfo, HtmlTextWriter writer)
    {
        RadioButton radioButton = new RadioButton();
        radioButton.Page = this.Page;
        radioButton.GroupName = "radioButtonGroup";
        radioButton.ID = this.ClientID + "_" + repeatIndex.ToString();
        radioButton.Text = this.Items[repeatIndex].Text;
        radioButton.Attributes["value"] = this.Items[repeatIndex].Value;
        radioButton.Checked = this.Items[repeatIndex].Selected;
        radioButton.TextAlign = this.TextAlign;
        radioButton.AutoPostBack = this.AutoPostBack;
        radioButton.TabIndex = this.TabIndex;
        radioButton.Enabled = this.Enabled;

        radioButton.RenderControl(writer);
    }
}

So that's just a simple extentension where I set the GroupName to be sure that all the radiobuttons created by that RadioButtonList have the same GroupName so that now, if anyone selects a value from RadiobuttonList1, it deselects any value they have selected in Radiobutton2 and vice versa (so they are mutually exclusive sets of radiobuttons).

Note: The radiobuttonlists are definitely being binded via a method call that's wrapped in a check for !Page.IsPostBack so that is not the issue here.

Here is an example where I'm using it in my .aspx page:

 <aj:CustRadioButtonList checked="false"  ID="rblEmail" runat="server" />

 <aj:CustRadioButtonList checked="false"  ID="rblReason" runat="server" />

Here in my code-behind, I'm checking for the selectedValue from the rblEmail within an onclick even of a button on my page..but it always returns empty string even if I have selected an item in the list:

    protected void btnContinue_Click(object sender, EventArgs e)
    {
        _actionID = rblEmail.SelectedValue;

I've spent an entire day around trying to figure out now why I keep getting an emptystring when clearly I have selected a value in rblEmail. Same holds true for the other radiobuttonlist rblReason. In either case, when checking from code-behind I get emptystring for SelectedValue.

If you look at the markup, here's how it looks:

<table id="rblEmail" checked="false" border="0">
    <tr>
        <td><input id="rblEmail_0" type="radio" name="radioButtonGroup" value="0" /><label for="rblEmai_0">All Offers</label></td>

    </tr><tr>
        <td><input id="rblEmail_1" type="radio" name="radioButtonGroup" value="1" /><label for="rblEmail_1">week</label></td>
    </tr><tr>
        <td><input id="rblEmail_2" type="radio" name="radioButtonGroup" value="2" /><label for="rblEmail_2">month</label></td>
    </tr><tr>
        <td><input id="rblEmail_3" type="radio" name="radioButtonGroup" value="3" /><label for="rblEmail_3">Holiday</label></td>
    </tr>

</table>
            </div>
...

<table id="rblReason" checked="false" border="0">
    <tr>
        <td><input id="rblReason_0" type="radio" name="radioButtonGroup" value="1" /><label for="rblReason_0">I receive</label></td>
    </tr><tr>
        <td><input id="rblReason_1" type="radio" name="radioButtonGroup" value="2" /><label for="rblReason_1">I have no need</label></td>
    </tr><tr>
        <td><input id="rblReason_2" type="radio" name="radioButtonGroup" value="3" /><label for="rblReason_2">Other</label></td>

    </tr>
</table>