i'm trying to add a key and value to the hashtable and then put that hashtable in Session and this works fine but i'm getting error when i try to browse to different pages in gridview and here is the error message:

Item has already been added. Key in dictionary: '0'  Key being added: '0' gridview

here is my code:

Hashtable ht = new Hashtable();  //declare in class level variable

 protected void gv_RowDataBound(object sender, GridViewRowEventArgs e)
 {
        ............
        ........

        ht.Add(e.Row.RowIndex, _sParameters); //error here
        //Session.Add("alertmessages", ht);
        Session["alerts"] = ht;
}

how should i deal with it?

thanks.

Hashtable ht = new Hashtable();

protected void gv_RowDataBound(object sender, GridViewRowEventArgs e)
{
   if(!ht.Contains(e.Row.RowIndex))
   { 
      ht.Add(e.Row.RowIndex, _sParameters); //no error here 
   }
  //Session.Add("alertmessages", ht); Session["alerts"] = ht; 
}