Forms Data Controls :: Row Data Bound Method That Inserts A Row When Comparing Values On A Particular Field

I have a gridview, which on the row data bound method that inserts a row when comparing values on a particular field. If the two values are different, a new row is inserted, if not no row is inserted. This coding is working as a grouping gridview, and is working correctly. However, I have problem, and problem is counting the rows between each group, which I want to display in my blank row between each group, the value of which I am holding in a hiddenfield.

When I try to do it, the first group doesn't show the result, but is displayed on the next group. I am pretty sure that I am doing something wrong. My approach is that if the value between the last row and the existing row are different, then the value is one, on the next row data bound event, if the values are the same then the value is increased by one, else the value is one because it is a new group. Here is my code:

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
Table tbl = e.Row.Parent as Table;
TableCell cell = new TableCell();
CheckBox chk = new CheckBox();
Label lbl2 = new Label();
HiddenField rowValue = new HiddenField();
if (e.Row.RowType == DataControlRowType.Header)
{
e.Row.Visible = false;
}
else
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
Session["count"] = 1;
Label lbl = (Label)e.Row.FindControl("lblValue");
string str1 = ((Label)(lbl)).Text;
string prevStr= (string)Session["previousStr"];
if (prevStr== str1)
{
lbl.Visible = false;...................