[amibroker] Multi Timeframe Signals

[yund]

I trying to optimize some parameters using multiple time frames.  I'm 
getting the Buy/Sell signals but the signals are not there when I 
"Scan" or "Back Test".

Can someone help me with this?

Here is an example:

//////// Code Snipit - Begin
TimeFrameSet(TimeFrameFast);
CCIFast = CCI(PeriodFast );
TimeFrameRestore();

TimeFrameSet(TimeFrameSlow);
CCISlow = CCI(PeriodSlow );
TimeFrameRestore();

CCIBuyExFast = TimeFrameExpand(CCIFast, TimeFrameFast);
CCIBuyExSlow = TimeFrameExpand(CCISlow, TimeFrameSlow);

Buy = Cross(CCIBuyExFast, CCIBuyExSlow);
//////// Code Snipit - End


The signal is there when i:
Plot( Buy , "CCI Buy - " + PeriodFast, colorGreen );

But nothing in "Scan" or "Back Test", please help !!

Thank you,
-Dave