The type or namespace name 'OracleClient' doesn't exist in the namespace 'System.Data' (Are you missing an assembly reference?)

Hello:

I have 2 systems - 2k8 server with oracle 32bit and 2k8 server with oracle 64bit.

I am testing the same OracleChk.aspx page on both systems. 

2k8 server with oracle 32 bit gives no errors.

2k8 server with oracle 64bit gives the following errors:

error cs0234: The type or namespace name 'OracleClient' doesn't exist in the namespace 'System.Data' (Are you missing an assembly reference?)

Does it mean OracleClient only work on Oracle 32 bit?  Please advice.  thanks

using System;
using System.Data;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Data.OracleClient;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class CheckOra : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

        OracleConnection sConn = new OracleConnection("Password=xxx;User ID=xxx;Data Source=Hello.WORLD;Persist Security Info=True;");

        try
        {
            sConn.Open();
            Response.Write("Successfully Opened");
        }
        catch (Exception ex)
        {
            Response.Write("Could not establish connection:<br /><br />" + ex.Message);
        }
    }
}