Intermittent Invalid Viewstate Error in ASP.NET Web pages [Resolved]

Im developing a Chart that is displaying Farmer Status (current status, pending status etc...)
the for the click status from a reapter using linkbutton it is working ...
but when i close google chart and try to selet another farmer status it getting error ... *

[ViewStateException: Invalid viewstate.
Client IP: ::1
Port: 27968
Referer: http://localhost/HolidayTracker/Report/VacationChart.aspx
Path: /HolidayTracker/Report/VacationChart.aspx
User-Agent: Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; WOW64; Trident/6.0)
ViewState: ....

protected void rpStatus_ItemCommand(object source, RepeaterCommandEventArgs e)
    {
        try
        {
            if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
            {
                if (e.CommandName == "Status")
                {
                    this.dgFarmerDetail.DataSource = null;
                    this.dgFarmerDetail.DataBind();

                    this.dFarmerDetails.Visible = false;

                    this.dDetailHead.Visible = false;
                    this.dfarmerHead.Visible = false;

                    StatusID = Convert.ToInt32(e.CommandArgument);

                    this.SetFarmerChart();
                    ScriptManager.RegisterStartupScript(this, this.Page.GetType(), "updatePanel1Script", "javascript:drawFarmerChart();", true);
                }
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

 public string SetFarmerChart()
    {
        DataTable sourceFarmer = null;
        StringBuilder returnFarmerValue;
        int incVal;
        FarmerLogic farmerLogic;
        FarmerEntity farmerEntity;

        try
        {
            returnFarmerValue = new StringBuilder();

            farmerEntity = new FarmerEntity();

            if (StatusID == 0)
            {
                farmerEntity.UserID = GM.UserID;
                farmerEntity.StatusID = 0;         
            }
            else if (StatusID > 0)
            {
                farmerEntity.UserID = GM.UserID;
                farmerEntity.StatusID = StatusID; 
            }

            farmerLogic = new FarmerLogic();

            sourceFarmer = farmerLogic.SelectFarmerMasterStatusChart(farmerEntity);

            if (sourceFarmer == null) { sourceFarmer = null; return string.Empty; }
            if (sourceFarmer.Rows.Count <= 0) { sourceFarmer = null; return string.Empty; }

            if (sourceFarmer.Rows.Count > 0 && Convert.ToInt32(sourceFarmer.Rows[0]["TotalStatus"].ToString()) != 0)
            {
                returnFarmerValue.Append("data.addColumn('string', 'Status');");
                returnFarmerValue.Append("data.addColumn('number', 'TotalStatus');");

                returnFarmerValue.Append("data.addRows(" + sourceFarmer.Rows.Count + ");");

                for (incVal = 0; incVal < sourceFarmer.Rows.Count; incVal++)
                {
                    returnFarmerValue.Append("data.setValue(" + incVal + ", 0, '" + sourceFarmer.Rows[incVal]["Status"] + "');");
                    returnFarmerValue.Append("data.setValue(" + incVal + ", 1, " + sourceFarmer.Rows[incVal]["TotalStatus"] + ");");
                }

                return returnFarmerValue.ToString();
            }
            else
            {
                return returnFarmerValue.ToString();
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {
            sourceFarmer = null;
            farmerLogic = null;
            farmerEntity = null;
        }
    }

[Resolved]