I'm trying to set the width of one or a few cells in Excel.

This is my code

```
Microsoft.Office.Interop.Excel.Application xla = new    
      Microsoft.Office.Interop.Excel.Application();
Workbook wb = xla.Workbooks.Add(XlSheetType.xlWorksheet);
Worksheet ws = (Worksheet)xla.ActiveSheet;

```

i know if i going to change entire columns width 

```
ws.Columns.ColumnWidth = 30;
ws.Cells.ColumnWidth = 30;

```

but when i try to change spesific columns with this following code

```
ws.Columns[5].ColumnWidth = 30; 
*//or* 
ws.Cells [5, 5].ColumnWidth = 30;
**//or* 
ws.Columns["E:E"].ColumnWidth = 30;

```

property `ColumnWidth` can't be used  

in list after i type colums[5] then dot just appear 'Equals, GetHahCode, Gettype, ToString'
when i try to manually type it
**it's give error 'No Overload for method 'this' takes '1' argument'**

i used visual studio 2010 and framework 4.0
I wonder what I'm missing ...