Modification to PRPayGroupPeriod causes errors

/*

  I added a customization project with a single code file:

*/

using PX.Data.ReferentialIntegrity.Attributes;
using PX.Data;
using PX.Objects.Common.Attributes;
using PX.Objects.GL.Attributes;
using PX.Objects.GL;
using PX.Objects.PR;
using PX.Objects;
using System.Collections.Generic;
using System;

/*

  This field was already added to the database table with a default constraint value of false.

*/
namespace PX.Objects.PR
{
  public class PRPayGroupPeriodExt : PXCacheExtension<PX.Objects.PR.PRPayGroupPeriod>
  {
    #region SwipeAndConfirmationLock
    [PXDBBool()]
    [PXDefault(false)]
    [PXUIField(DisplayName="Swipe And Confirmation Lock")]
    public virtual bool SwipeAndConfirmationLock { get; set; }
    public abstract class swipeAndConfirmationLock: PX.Data.BQL.BqlBool.Field<swipeAndConfirmationLock> { }
    #endregion
  }
}

/*

   When navigating to Paychecks and Adjustments the following error occurs:

   Error: An error occurred during processing of the field Swipe And Confirmation Lock: Object reference not set to an instance of an object..

  I do not want to modify any screens at this time.  There are no other customizations on the instance of Acumatica.

  Any ideas?  

*/