Foreign function and open interest EXAMPLE

["nenapacwanfr" <nenapacwanfr@xxxx>]

Clo= Foreign("SP500-1","C");
Opi= Foreign("SP500-1","OI");


this works:
Plot(((C/OI)+1)*50,"",1,1);

this does not works:
Plot(((Clo/Opi)+1)*50,"",1,1);

Stephane