using c# to select a worksheet in excel

Using C# in .NET 3.5 with Visual Studio 2008, I am trying to set focus (or activate) a specific worksheet in an open workbook: Here are some properties: ``` public Excel.Application xlApp {get;set;} public Excel.Workbook xlWorkBook { get; set; } public Excel.Worksheet xlWorkSheet { get; set; } public Excel.Range range { get; set; } ``` And here is how I am trying to select a specific worksheet: ``` (xlWorkSheet)Application.ActiveWorkbook.Sheets[FormControls.WorksheetFocus]).Select(Type.Missing); ``` And I have also tried this way: ``` ((Excel.Worksheet)this.Application.ActiveWorkbook.Sheets[1]).Select(); ``` What am I doing wrong? How do I select a specific worksheet in a workbook using C#? explanation of where the definitions are: ``` namespace EmailSalesVolumeSolution { class WorkBook { public string MasterFileName { get; set; } public string[] DistinctEmails { get; set; } public Excel.Application xlApp {get;set;} public Excel.Workbook xlWorkBook { get; set; } public Excel.Worksheet xlWorkSheet { get; set; } public Excel.Range range { get; set; } ``` and everything is in the same class and namespace here is how it is initiliazed: ``` private void OpenWorkBook() { string str; int rCnt = 0; int cCnt = 0; xlApp = new Excel.ApplicationClass(); xlWorkBook = xlApp.Workbooks.Open(MasterFileName, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0); xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(FormControls.WorksheetEmails); ```