Form Level Fields are ENABLE/Disable based on the other field

Dear Frnds

                   I have one requirement  , i am doing the new form in that overview, General & Accrual three tab pages are three

In overview grid Accrual field (yes/no combo box type), if i select "yes" then only accrual Tab fields are Enable otherwise Disable

in data source , Accrual field i wrote a modified method like as follows below 

public void modified()

{

    super();

     if (CEMPAbsence.Accrual == Accrual::Yes )

    {

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,AccrualType)).enabled(True);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,Numberofunits)).enabled(True);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,Rule)).enabled(True);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,Accrueperiod)).enabled(True);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,FromDate)).enabled(True);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,Accrueperiodunit)).enabled(True);

    //element.SetAccrual();

    }

    else

    {

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,AccrualType)).enabled(false);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,Numberofunits)).enabled(false);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,Rule)).enabled(false);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,Accrueperiod)).enabled(false);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,FromDate)).enabled(false);

        CEMPAbsence_ds.object(fieldNum(CEMPAbsence,Accrueperiodunit)).enabled(false);

    }

    CEMPAbsence_ds.reread();

    CEMPAbsence_ds.refresh();

}

but one problem is there  when i reopen the form

this one is not working

can u plz give the suggestion any body