[amibroker] Previous close prices on n = -1 MACD cross?

["Quad Rate Serial Abby" <quad_pumped_abby@xxxxxxxxx>]

I am trying to write code that will return the closing price on the 
date of the last cross of the signal line by the MACD line prior to 
a cross of the same type occuring today.  I have a selectio of code 
here, but am getting a syntax error trying to use the ValueWhen 
function.  Does anybody see anything wrong with this? TIA.

RET_1 = Prefs( 11 );
RET_2 = Prefs( 12 );
RET_3 = Prefs( 13 );

M_LINE = MACD(RET_1, RET_2);
S_LINE = Signal(RET_1, RET_2, RET_3);

PRES_CROSS = Cross(M_LINE, S_lINE);
PREV_CROSS = Ref(Cross(M_LINE, S_LINE), -1);

PREV_CLOSE = ValueWhen(Ref(Cross(M_LINE, S_LINE), -1) C, 1);





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