C# WinApp สงสัยเกี่ยวกับ การนำ Control มาลงใน navigator ครับ

โค้ดเป็นแบบนี้ครับ

namespace System.WindowsTOR.Forms
{
    using System;
    using System.Drawing;
    using System.Drawing.Design;
    using System.ComponentModel;
    using System.Diagnostics;
    using System.Windows.Forms.Layout;
    using System.Collections.Specialized;
    using System.Runtime.InteropServices;
    using System.Windows.Forms.Design;
    using System.Security;
    using System.Security.Permissions;
    using Microsoft.Win32;
    using System.Windows.Forms;
    using System.Globalization;

    [ToolStripItemDesignerAvailability(ToolStripItemDesignerAvailability.ToolStrip)]
    public class ToolStripDateTimePicker : ToolStripControlHost
    {
        private FlowLayoutPanel controlPanel;
        private DateTimePicker picker = new DateTimePicker();

        public ToolStripDateTimePicker()
            : base(new FlowLayoutPanel())
        {
            controlPanel = (FlowLayoutPanel)base.Control;
            picker.Format = DateTimePickerFormat.Long;
            picker.Value = DateTime.Now;
            this.picker.ValueChanged += new System.EventHandler(this.dateTimePicker_ValueChanged);
            controlPanel.BackColor = Color.Transparent;
            controlPanel.Controls.Add(picker);
        }
        string _CustomFormat;
        [EditorBrowsable(EditorBrowsableState.Always)]
        [Browsable(true)]
        [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        [Bindable(true)]
        public string CustomFormat
        {
            get
            {
                return _CustomFormat;
            }

            set
            {
                _CustomFormat = value;
                if (DateTimeFormat == DateTimePickerFormat.Custom)
                {
                    picker.CustomFormat = value;
                }

            }
        }

        DateTimePickerFormat _DateTimeFormat;
        [EditorBrowsable(EditorBrowsableState.Always)]
        [Browsable(true)]
        [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        [Bindable(true)]
        public DateTimePickerFormat DateTimeFormat
        {
            get { return _DateTimeFormat; }
            set { _DateTimeFormat = value; picker.Format = value; }
        }
        DateTime _Value;
        [EditorBrowsable(EditorBrowsableState.Always)]
        [Browsable(true)]
        [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        [Bindable(true)]
        public DateTime Value
        {
            get { return _Value; }
            set { _Value = value; this.picker.Value = value; }
        }
        protected override void OnPaint(PaintEventArgs e)
        {
            this.picker.Value = DateTime.Now;
        }

        protected override void OnSubscribeControlEvents(Control control)
        {
            base.OnSubscribeControlEvents(control);
        }
        protected override void OnUnsubscribeControlEvents(Control control)
        {
            base.OnUnsubscribeControlEvents(control);
        }

        private EventHandler onValueChanged;
        protected virtual void OnValueChanged(EventArgs eventargs)
        {
            if (onValueChanged != null)
            {
                onValueChanged(this, eventargs);
            }
        }
        public event EventHandler ValueChanged
        {
            add
            {
                onValueChanged += value;
            }
            remove
            {
                onValueChanged -= value;
            }
        }
        private void dateTimePicker_ValueChanged(object sender, EventArgs e)
        {
            if (onValueChanged != null)
            {
                onValueChanged(this, e);
            }
        }
    
    }

}


พอเรา เอาไปลง navigator รันโค้ดแล้ว value ไม่เปลี่ยนตาม CustomFormat ครับ
จะเป็น dd/MM/yyyy เช่น 23/1/2560 ครับ
ทั้งๆที่ DateTimeFormat กับ Value ก็ตั้งได้ครับ แต่ติดตรง CustomFormat