[amibroker] Why do I get "missing buy/sell variable assignmets" error?

[alta hob]

I`m trying to run this code as a simple backtest but get "missing buy/sell
variable assignmets" error.  Have tried adding

ApplyStop( stopTypeNBar, stopModeBars, 5 );

but  still get error.   Can someone please advise what I need to do to run
as  a simple backtest with a trailing bar stop?

thanks

altahob
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/* Connors and Raschke Historical Volatility System
    For further explanation, refer to "Street Smarts"
    from Connors and Raschke.
    Ported from Metastock code by Daniel Ervi           */

numcolumns = 5;

VolRatio =  StDev(Log(C/Ref(C,-1)),5) / StDev(Log(C/Ref(C,-1)),99);
column0 =  VolRatio;
column0name = "VolRatio";

NR4Day = (H - L) < Ref(LLV(H-L,3),-1);
column1 =  NR4Day;
column1name = "Nr4Day";

InsideDay = H < Ref(High,-1) AND Low > Ref(Low,-1);
column2 =  InsideDay;
column2name = "Inside Day";

column3 =  High + 0.125;
column3name = "Buy Stop";

column4 =  Low - 0.125;
column4name = "Sell Stop";

filter = VolRatio < 0.5 AND (NR4Day == 1 AND InsideDay == 1);

buy = filter;