'DocumentFormat.OpenXml.Spreadsheet.WorksheetExtensionList' from assembly 'DocumentFormat.OpenXml

i have a got the this error

'DocumentFormat.OpenXml.Spreadsheet.WorksheetExtensionList' from assembly 'DocumentFormat.OpenXml, Version=2.5.4728.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.

i have used this code in below

private void button1_Click(object sender, EventArgs e)
    {
        XLWorkbook workbook = new XLWorkbook();
        IXLWorksheet worksheet = workbook.Worksheets.Add("Sample Sheet");
        worksheet.Cell("A1").Value = "Hello World!";
        string folderPath = "C:\\User\\test\\Desktop\\";
        if (!Directory.Exists(folderPath))
        {
            Directory.CreateDirectory(folderPath);
        }
        workbook.SaveAs(folderPath + "sanjay.xlsx");

    }

i have simple create the test project and i am using the ClosedXml and simple project will run then button click then open excel file just simple any body help me

Advance thank you
Mr.Malakiya