Radio Button List Item Using Javascript

I am having one radio button list.

<asp:RadioButtonList ID="rdHealthCleared" runat="server"
CssClass="radiobtn" AutoPostBack="true" OnClick="showRadioCheckBox()"
CausesValidation="false" CellPadding="0" CellSpacing="0" Width="275px">
<asp:ListItem id="rdNotCleared" runat="server" Text="Not Cleared" Value="1"/>
<asp:ListItem id="rdPending" runat="server" Text="Pending further Info from Applicant" Value="2"/>
<asp:ListItem id="rdCleared" runat="server" Text="Cleared" Value="3" />
</asp:RadioButtonList>

I am using three check boxes. If i click first radio button list item, the first check box need to show. In the same scenario for another two radio button list items and checkboxes. How can we done in javascript. i call it the onclick function and put it node value for this condition but when in alert the node value is giving null. this is my java script code.

var uxNotClearedObj = document.getElementById('uxOHCNotCleared2');
//alert(uxNotClearedObj);
var uxPendingObj = document.getElementById('uxOHCPending2');
// alert(uxPendingObj);
var uxClearedObj =document.getElementById('uxOHCCleared2');
//alert(uxClearedObj);
var rdPendingObj = document.getElementById('rdPending');
// alert(rdPendingObj);
var rdClearedObj = document.getElementById('rdCleared');
var rdNotClearedObj = document.getElementById('rdNotCleared');
// alert(rdClearedObj);
var rdHealthClearedObj = document.getElementById('rdHealthCleared');.....................