Error creating custom Textbox Control

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C#

ASP.NET

Hi,

am creating a custom web control which have boolean property isRequred. At the runtime the control just works fine without any problem. there is no problem whatsoever. But at the design time it shows this error in place of control ...

When We drag the control from the toolbox in the desiger. the controls does not generates besides it write following message in place of control

Error creating control - ExcelTextBox
true cannot be set on property 'Required'





Code is as below : =

private bool required = false;
private RequiredFieldValidator req = null;

public bool Required
               {
                   get
                   {
                       return this.required;
                   }
                   set
                   {
                       this.required = value;
                   }
               }
protected override void OnInit(EventArgs e)
      {
          Controls.Clear();
          this.ID = base.ID;
          if (Required)
          {
              req = new RequiredFieldValidator();
              req.ID = "rfv" + this.ClientID;
              req.ControlToValidate = this.ClientID;
              req.ValidationGroup = this.ValidationGroup;
              req.ErrorMessage = ErrorMessage;
              req.Text = "*";
              req.EnableClientScript = (this.ClientScript.ToLower() != "false");
              this.Controls.Add(req);
          }

}

protected override void Render(HtmlTextWriter w)
       {
           base.Render(w);
           if (Required)
           {
               req.RenderControl(w);
           }
}

What is the reason behind getting error

Please help me in this regard......