save buttons click event not being fired on clicking

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ASP.NET4

I am facing a very different problem, i have made a button save and defined its onsaveclick, but no event is being fired on clicking that button,however it is working for the other two buttons.. below is my code: on region.ascx

<lpsfsu:CommandBar ID="fsucCommandBarItemCostAdjustment"  runat="server" DefaultPanel="pnlZoneMaintenanceItemCostAdjustmentControls"
           DisplayButtons="Save,Submit,Cancel" AutoPostbackButtons="Save,Submit,Cancel"
           ValidationGroup="grpVldZoneMaintenance" CauseValidationOnCancel="false" ButtonPosition="Right"
           DefaultPanelButton="Save" OnSaveClick="btnSave_Click" OnCancelClick="btnCancel_Click"
            önSubmitClick="btnSubmit_Click" />

on regionascx.cs

protected void btnSave_Click(object sender, EventArgs e)
      {
          // This is save in Draft mode.
          try
          {
              if (_currentTabMode.Equals(ZoneMaintenanceFormMode.Approval))
              {
                  if (ValidateComments())
                  {
                      // Record to be Approved
                      CurrentViewContext.ViewContract.ZoneStatus = ZoneMaintenanceStatus.Approved;

                      // Set Approved in Queue
                      String errorCode = Presenter.SaveZoneToQueue();

                      // Set Approved in DB Only in case of define zone.
                      Presenter.SaveItemZoneCosts();

                      grdItemCostAdjustment.Rebind();

                      ProcessErrorCode(errorCode);

                      _currentTabMode = ZoneMaintenanceFormMode.ReadOnly;

                      ShowCommentHistory(CurrentViewContext.ViewContract.TransactionId);

                      //After Approve move to the parent page
                      RedirectToOriginatedPage();
                  }
              }
              else
              {
                  Int32 zoneId = _viewContract.IsNull() ? SysXConsts.MINUS_ONE : _viewContract.ZoneId;

                  // Validate controls
                  if (ValidateControls())
                  {
                      // Create/Update Define Zone Context in Queue
                      CurrentViewContext.ViewContract.ZoneStatus = ZoneMaintenanceStatus.Draft;

                      // Display appropriate message based on error code
                      ProcessErrorCode(Presenter.SaveZoneToQueue());

                      //Save value in DB in with IsApproved = 0
                      Presenter.SaveItemCosts();

                      ShowCommentHistory(CurrentViewContext.ViewContract.TransactionId);

                      //set ids in viewstate
                      ViewState[SysXZoneMaintenanceConst.ZONEMAINTENANCE_ITEM_COST_TRANSACTIONID] = CurrentViewContext.ViewContract.TransactionId;
                  }

              }

          }