Update panel and back button

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C#

ASP.NET

UpdatePanel

, +

Hi everyone,
in an .aspx page I have multiple update panels in each there's whether dropdownlist or a repeater.
Of course once there's an updatepanel a problem with browser back button.
I managed to re-set all the (cascading) dropdownlists when click back button, but binding the repeater with data I'm not able to do.

So My questions are:
1- the proper way to user Script manager AddHistoryPoint (using all history points in the last dropdownlist otherswise is not gonna work).
2-Add history point to a repeater and manage the scriptmanager Navigate.

Thanks in advance
Samira

What I have tried:

**Adding History point to the drop downlists //from trim dropdownlist:

protected void DropDownListTrim_SelectedIndexChanged(object sender, EventArgs e)
        {
//some code
ScriptManager.GetCurrent(this.Page).AddHistoryPoint("yearid", DropDownListAnnee.SelectedItem.Value);
            ScriptManager.GetCurrent(this.Page).AddHistoryPoint("year", DropDownListAnnee.SelectedItem.Text);
            ScriptManager.GetCurrent(this.Page).AddHistoryPoint("modelid", DropDownListModele.SelectedItem.Value);
            ScriptManager.GetCurrent(this.Page).AddHistoryPoint("model", DropDownListModele.SelectedItem.Text);
            ScriptManager.GetCurrent(this.Page).AddHistoryPoint("trimid", DropDownListTrim.SelectedItem.Value);
            ScriptManager.GetCurrent(this.Page).AddHistoryPoint("trim", DropDownListTrim.SelectedItem.Text);
}

**set selected values of the dropdownlists (not sure if this is the correct way to do this)

 protected void ScriptManager1_Navigate(object sender, HistoryEventArgs e)
        {
//it does set the selected values but for sure the dropdownlists don't have any other values!
//the dropdownlists are empty
DropDownListAnnee.SelectedValue = e.State["yearid"];
DropDownListAnnee.SelectedItem.Text = e.State["year"];
DropDownListModele.SelectedItem.Value = e.State["modelid"];
 DropDownListModele.SelectedItem.Text = e.State["model"];
DropDownListTrim.SelectedItem.Value = e.State["trimid"];
 DropDownListTrim.SelectedItem.Text = e.State["trim"];
}