We have a new video about plotting with procedures, specifically on how to avoid an error related to evaluation that many people make.
The worksheet I used in the video is available here: PlottingWithProcedures.mw
By the way, this mistake doesn't occur just in the context of plotting. Users of Optimization commands (and other commands that allow functions to be expressed as either an expression in a variable or as a procedure) frequently run into this problem too.
The last ten posts I see are spam!
Isn't it possible to stop them from spaming this Forum?