Thanks!
Could this line be changed for future to be this...
if ((graphicCollection != null) && (graphicCollection.length))
If I use the 2.3 api, with no code changes on my part, my code works. If I move to 2.4 api, it crashes on this line. I'm going to look in my code to see what I can do to fix this - maybe I haven't set something up correctly. Obviously the graphicCollection is null for some reason.