How to disable the image url icon even if not set to url ie but working fne in Firefox and chrome

protected string GetImgURL(bool IsGoodRepair)
{
   return (IsGoodRepair == true) ? "../../App_Themes/MainTheme/Icon/tick.gif" :"";
}

 protected void btnROfIEvaluation_Click(object sender, EventArgs e)
{
   try
   {
      string actionPerformed = string.Empty;
      this.lblAutoSave.Visible = false;
      this.lblAutoSave.Text = string.Empty;

      int currentYear = Convert.ToInt32(Session["CurrentYear"]) - 1;
      Services objServices = new Services(Convert.ToInt32(Session["CurrentYear"]));
      List<facilityinspectionsdo> objFacilityInspectionsDOList = new List<facilityinspectionsdo>();
      bool ReasonCheck = false;
      string reasons = "Provide comments for ";

      int InspectionID;

      foreach (GridViewRow objGridViewRow in this.GVInspection.Rows)
      {
         InspectionID = Convert.ToInt32(GVInspection.DataKeys[objGridViewRow.RowIndex].Values[0]);

         if (objGridViewRow.RowType == DataControlRowType.DataRow)
         {
            CheckBox chkExemplary = ((CheckBox)objGridViewRow.FindControl("chkExemplary"));
            CheckBox chkIsGood = ((CheckBox)objGridViewRow.FindControl("ChkIsGoodRepair"));
            CheckBox chkIsFair = ((CheckBox)objGridViewRow.FindControl("ChkIsFairRepair"));
            CheckBox chkIsPoor = ((CheckBox)objGridViewRow.FindControl("ChkIsPoorRepair"));
            TextBox txtAction = ((TextBox)objGridViewRow.FindControl("txtAction"));

            //if (InspectionID != 9)
            //{
            //    if ((!chkIsGood.Checked && !chkIsFair.Checked && !chkIsPoor.Checked) && txtAction.Text.Trim().Length == 0)
            //    {
            //        ReasonCheck = true;
            //        reasons += " \\n " + ((Label)objGridViewRow.FindControl("LblInspectionDesc")).Text;
            //    }

            //}
            //else if (InspectionID == 9)
            //{
            //    if (!chkExemplary.Checked && !chkIsGood.Checked && !chkIsFair.Checked && !chkIsPoor.Checked)
            //    {
            //        ReasonCheck = true;
            //        reasons = "Please select Repair Status for \\n " + ((Label)objGridViewRow.FindControl("LblInspectionDesc")).Text;
            //    }
            //}

            FacilityInspectionsDO objFacilityInspectionsDO = new FacilityInspectionsDO();
            objFacilityInspectionsDO.Year = currentYear;
            objFacilityInspectionsDO.CDS = Session["SelectedCDS"].ToString();
            objFacilityInspectionsDO.InspectionID = Convert.ToInt32(GVInspection.DataKeys[objGridViewRow.DataItemIndex].Value);
            objFacilityInspectionsDO.LANGUAGE = this.ddlLanguage.SelectedValue.ToString();

            if (chkIsGood.Checked)
               objFacilityInspectionsDO.IsGoodRepair = 2;
            else if (chkIsFair.Checked)
               objFacilityInspectionsDO.IsGoodRepair = 3;
            else if (chkIsPoor.Checked)
               objFacilityInspectionsDO.IsGoodRepair = 4;

            if (InspectionID == 9)
            {
               if (chkExemplary.Checked)
                  objFacilityInspectionsDO.IsGoodRepair = 1;

                            objFacilityInspectionsDO.Action = string.Empty;
            }
            else
               objFacilityInspectionsDO.Action = txtAction.Text;

            objFacilityInspectionsDOList.Add(objFacilityInspectionsDO);

            ((Label)objGridViewRow.FindControl("lblAction")).Text = txtAction.Text;
            Image imgIsGoodRepair = (Image)objGridViewRow.FindControl("imgIsGoodRepair");
            imgIsGoodRepair.ImageUrl = GetImgURL(chkIsGood.Checked);
         }
      }
      if (ReasonCheck == false)
      {
         actionPerformed = objServices.SaveFacilityInspections(objFacilityInspectionsDOList);
         ((SchoolPlan.NavigationPages.SARCInput)this.Page).InsertApplicationLog(actionPerformed, "Section3_SchoolFacilities_Ver2.ascx/btnROfIEvaluation_Click");
         rebindInspectionGrid();
   }
   //else
   //{
   //    reasons = reasons.Trim();
   //    ScriptManager.RegisterStartupScript(this, this.GetType(), "ReasonMsg", "<script language='javascript'> alert('" + reasons + "'); </script>", false);
   //}
   SaveInspectionDate();
   SetStatus();
   }
   catch (Exception ex)
   {
      LogException(ex);
   }
   //catch (Exception ex)
   //{
   //    //  ScriptManager.RegisterStartupScript(this, this.GetType(), "msg", "<script language='javascript'> alert('Error Occured'); </script>", false);
   //    RadAjaxManager rad = (RadAjaxManager)this.Page.Master.FindControl("RadAjaxManager1");
   //    rad.ResponseScripts.Add(string.Format("alert('Error: {0}');", ex.Message.ToString()));
   //}
}