full post back occurs

[System.Web.Services.WebMethod]
        public static string Gettype(string type)
        {
            return type ;

        }

i get type as blank

 protected void posyback_Click(object sender, EventArgs e)
        {
           
            try
            {
 	

                Qry = " SELECT FTYPE FROM STATUS,";
              
                SqlCommand cmd = new SqlCommand(Qry, con);
                SqlDataReader reader = cmd.ExecuteReader();

                if (reader.HasRows)
                {
                    while (reader.Read())
                    {

                        H_TYPE.Value = reader["FTYPE"].ToString();
                        }}

ScriptManager.RegisterClientScriptBlock(this, typeof(System.Web.UI.Page), "settype", "settype();", true);


                BindGrid();//function for binding grid
}
}

gettype is fired only after

ScriptManager.RegisterClientScript..............

function settype()
 {
PageMethods.Gettype(document.getElementById("<%=H_TYPE.ClientID%>").value, OnSuccess);
alert ("hello");
}

though i get alert i get H_TYPE not defined


before this line i get the value in the hidden control
 ScriptManager.RegisterClientScriptBlock(this, typeof(System.Web.UI.Page), "settype", "settype();", true);
and after this passing to the static function  
but its blank
i checked the sample
the only difference is i activate the function on a button click event in code  as above

You are mixing AJAX with ClientScript both are differen things. Please comment what you exactly want to achive in a new thread and I'll provide you solution