I can confirm that the concavity=[] does not seem to be working in Maple 16.

There is a possible workaround for the problem though.

Try:

f := -(.1*(x+3))*(x-1)*(x-3.5);
Student[Calculus1][FunctionChart](f, x = -4 .. 4, title = "", concavity = [filled(white, white)], caption = "", gridlines)

This will print the graph without any visible fill or arrows indicating concavity.

You may want to email tech support and see if they are aware of the issue.

Good Luck!