[amibroker] CUSTOM OBV INDICATOR

[Alan]

QuotesPlus does not provide volume data for the S&P500 Index stock 
symbol !SPX so the normal OBV indicator does not work.  I would like to 
use New York Total Volume, stock symbol !NY-V as a substitute.  How do I 
get OBV to work with a foreign symbol such as !NY-V.  Does anyone have a 
solution for this problem or is there a better way to do this?