Problem in finding selected radio buttons in the Repeater

Hi,
I am new to asp.net..
Inside the repeater i am having 2 radiobutton  and a button.
On click of button i am trying to find the selected radio button in the itemtemplate. I am selecting a radio button in each repeater item.
On button click , i am iterating through repeater item and i am trying to find the selected radion  button.
But there, it is showing nothing is selected.
Ex:
<asp:Repeater runat="server" ID="repeater" >
 <ItemTemplate>
<asp:Label ID="Label2" Text='<%# Eval("QuestionTxt")%>' runat="server" />
<asp:RadioButton ID="Label3" Text='<%# Eval("Answer1")%>' runat="server" />
<asp:RadioButton ID="Label3" Text='<%# Eval("Answer2")%>' runat="server" />
<asp:Button Text="Submit the question" OnC ...