I want you to correct alerts in TOS strategy?

There is an input called PAS set at let's say 28, it needs to scan for previous alerts but it cannot pickup an old alert.. ... here is the code........... Tell me if you can tackle it...


input PreviousAlertScreening = 8;

def PrevBuyAlert = if PreviousAlertScreening == 0 then 0 else Highest(blabel, PreviousAlertScreening) ;
Alert(blabel or PrevBuyAlert, "B Signal", Alert.BAR, Sound.Ring);

def PrevSellAlert = if PreviousAlertScreening == 0 then 0 else Highest(slabel, PreviousAlertScreening);
Alert(slabel or PrevSellAlert, "S Signal", Alert.BAR, Sound.Ring);

def PrevXAlert = if PreviousAlertScreening == 0 then 0 else Highest(xlabel , PreviousAlertScreening) ;
Alert(xlabel or PrevXAlert, "X Signal", Alert.BAR, Sound.Ring);