Nothing is recorded and the formatting is lost

[GoogleCodeExporter]

What steps will reproduce the problem?
1.There is a file created in advance 1.xls (1.png)
2.I opened it with the code and try to write into the cell.
string file = "d:\\1.xls";
   // оpen xls file

 Workbook book = Workbook.Load(file);
sheet.Cells[5, 17] = new Cell(a1);
sheet.Cells[5, 18] = new Cell(c, "#,##0.00")
3.Nothing is recorded and the formatting is lost. (2.png)
What can tell how to write in a cell of an existing file?

What is the expected output? What do you see instead?

What version of the product are you using? On what operating system?
xp

Please provide any additional information below.

Original issue reported on code.google.com by manukovs...@gmail.com on 17 Feb 2012 at 10:09