Forms Data Controls :: Unable To Set Image Width (RowDataBound)

I need to specify image width dynamically (To get some progress bar effect). I wrote below code in RowDataBound

sender,GridViewRowEventArgs e)
{
if (e.Row.RowType ==
DataControlRowType.DataRow)
{
if (e.Row.Cells[2].Text !=
"Propulsion") // Propulsion is column name
{
string
s = e.Row.Cells[2].Text;
System.Web.UI.WebControls.Image
img = new System.Web.UI.WebControls.Image();
img.ImageUrl =
"http://localhost:47120/green_img.png";
img.Width =
new
Unit(Convert.ToInt32(s)+"px");
e.Row.Cells[2].Controls.Add(img);
}
}
}

void gridView_RowDataBound(object Error: Input string was not in correct format