getting the close value for symbols other than the current chart

[eparks]

How do I get the currnet values of (UPRO and SPXU) for within EFS when the EFS is on a chart with a different symbol.

I have tried:

A) tmpnum = close(0,sym("UPRO,1"));
B) tmpnum = close(0,0, "UPRO");
C) tmpnum = close(0,0, sym"UPRO,1"));

and

D)tmpnum = close(0,0, "UPRO,1");

all of the above return "nulll"

For some other symbols. sometimes "A" above returns a vlaue and sometimes "null"