querybuildrange object not initialised

I am getting this error in designList > Tree > Methods > Selection Changed.

public void selectionChanged(FormTreeItem _oldItem, FormTreeItem _newItem, FormTreeSelect _how)

{

    container   recIds;

    super(_oldItem, _newItem, _how);

    psaSummaryActivity.parmPSATmpSchedProjActivity(psaTmpSchedProjActivity);

    recIds = psaSummaryActivity.selectionChange(_newItem, psaProjTree.getSelection());

    canAssign = conPeek(recIds,4);

    qbr.value(queryValue(conPeek(recIds, 1)));

    qbr1.value(queryValue(conPeek(recIds, 2)));

    isSummary = conPeek(recIds,3);

    psaTmpSchedProjActivity_ds.executeQuery();

    //m_oResourceScheduling_Load.initTmpReservation(PSATmpSchedProjActivity.StartDate, PSATmpSchedProjActivity.EndDate);

    m_oResourceScheduling_Load.updateTables(psaTmpSchedProjActivity, true);

    resourceButtons.enabled(false);

    assignmentButtonGroup.enabled(false);

}

please advice aand let me know the solution for this error

Thanks in advance everyone for your help