How to return dataset in wcf

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.ServiceModel;


namespace WCFTemplateExample
{
    [ServiceContract]
    interface WCFInterface
    {
        [OperationContract]
        DataSet GetData();

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Data;

namespace WCFTemplateExample
{
   public  class WCFClass :WCFInterface 
    {
        #region WCFInterface Members

        public System.Data.DataSet GetData()
        {
            SqlConnection con = new SqlConnection(@"Data Source=iicss20\PMIS;Initial Catalog=MSSLMS;Persist Security Info=True;User ID=nkhn3059;Password=nkhn3059");
            SqlDataAdapter da = new SqlDataAdapter("select * from ss.lease",con);
            DataSet ds = new DataSet();
            da.Fill(ds, "ss.lease");
            return ds;

        }

        #endregion
    }
}

<system.serviceModel>
    <services>
      <service name="WCFTemplateExample.WCFClass" behaviorConfiguration="WCFTemplateExample.WCFClassBehavior">
        <host>
          <baseAddresses>
            <add baseAddress = "net.tcp://localhost:8731/Design_Time_Addresses/WCFTemplateExample/WCFClass/" />
          </baseAddresses>
        </host>
        <endpoint address="net.tcp://localhost:8008/WCFClass" binding="netTcpBinding" contract="WCFTemplateExample.WCFInterface"></endpoint>
        <!-- Service Endpoints -->
        <!-- Unless fully qualified, address is relative to base address supplied above -->
        <!--<endpoint address ="" binding="Binding" contract="WCFTemplateExample.WCFInterface">
          --><!--

              Upon deployment, the following identity element should be removed or replaced to reflect the
              identity under which the deployed service runs.  If removed, WCF will infer an appropriate identity
              automatically.
          --><!--
          <identity>
            <dns value="localhost"/>
          </identity>
        </endpoint>-->
        <!-- Metadata Endpoints -->
        <!-- The Metadata Exchange endpoint is used by the service to describe itself to clients. -->
        <!-- This endpoint does not use a secure binding and should be secured or removed before deployment -->
        <endpoint address="mex" binding="mexTcpBinding" contract="IMetadataExchange"/>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="WCFTemplateExample.WCFClassBehavior">
          <!-- To avoid disclosing metadata information,
          set the value below to false and remove the metadata endpoint above before deployment -->
          <serviceMetadata httpGetEnabled="false"/>
          <!-- To receive exception details in faults for debugging purposes,
          set the value below to true.  Set to false before deployment
          to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="False" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>