[amibroker] AFL - buys at bar low even when my buyprice is not hit

[Siva]

My AFL basically buys when MA(20)starts trending up. The system should buy only 
when my buyprice is hit.
var1 = MA( Close, 20 );
Cond1 = Ref( var1, -4 ) < Ref( var1, -5 ) ;
Cond2 = Ref( var1, -3 ) < Ref( var1, -4 );
Cond3 = Ref( var1, -2 ) > Ref( var1, -3 ) ;
Cond4 = Ref( var1, -1 ) > Ref( var1, -2 );
BuyPrice = Ref( Close, -1 ) - ( ATR(10) * 0.5 ) ;
Buy = Cond1 AND Cond2 AND Cond3 AND Cond4 ;

But when I back test the above formula, it buys at bar low even when my 
buyprice is not hit. How to avoid it buying at bar low? Thanks in advance.