I have a reference set to Infragistics2.Excel.v6.3

using System;
using System.Collections.Generic;
using System.Text;
using Infragistics.Excel;

namespace myNamespace
{
    class ExcelAdapter
    {
        Infragistics.Excel.Workbook workbook = null;

        public ExcelAdapter()
        {
            workbook = Infragistics.Excel.Workbook.Load("C:\\ExistingWorkbook.xls");     // this line fails to compile          
        }

...

I don't have a static Load method avaialable from the Workbook object. Any ideas as to why this might be? The VS.NET 2005 intellissnse for Infragisitcs.Excel.Workbook object is as follows:

.Equals
.MaxExcelCellFormatCount
.MaxExcelColorCount
etc...