Dynamically generated CheckBoxList value on postback

I've got an aspx page which doesn't have any predefined controls.I am rendering controls on the fly dinamically...  for checkbox i've the following code:

 CheckBoxList cntControl = new CheckBoxList();
cntControl.ID = Name;
cntControl.DataSource = Source;
cntControl.DataTextField = "description";
cntControl.DataValueField = "id";
//code goes here
span.Controls.Add (cntControl)
 
But on postback i need to get the values of the selected checkbox(s). I only have the option of Request.Form[Name]. But it's returning null as the HTML rendered is something like...<input id="cblOne_0" type="checkbox" name="cblOne:0" /><label for="cblOne_0">One</label>
<input id="cblOne_ ...