Hi DayanaArul,
Please refer to the following thread regarding this scenario:
http://forums.infragistics.com/forums/t/65505.aspx
Include height in the div style property
like this
e.Row.Cells.FromKey("ProgressBar").Value = "<div style='BACKGROUND-COLOR: olive;height:13 px; width:" + _ e.Row.Cells.FromKey("Completed").Value.ToString() + "%'></div>"