Hi Once the syntax of your code is corrected the simple fact is that neither expression should work, but if one is more correct than the other it’s the second one. Nevertheless over the years I’ve come across several examples where named variables fail to output the correct or any result while unnamed variables work just fine. The Ref(CLOSE,1) expression is always going to return N/A (no plot) on the last bar. Why? Because it’s forward referenced and on the last bar there is no data for it to look forward to. Since any N/A result within an expression (in this case the If() function) causes that expression to also return an N/A the "correct" response comes from the named variable, not the unnamed one. I suspect that the unnamed PREV variable returns a zero as an incomplete result from the PREV function whereas the structure of the named variable allows the PREV expression to return a correct result, namely N/A. I’m just guessing though. If there’s a point to your exercise it would seem to be to plot the following CLOSE except on the last bar plot the current CLOSE, and the code below does that. D:=IsDefined(Ref(C,1)); If(D,ExtFml("Forum.Sum",Ref(C,1),1),C); Roy