[Orgmode] Batch exporting a sparse tree

[Lindsay Todd]

I am trying to write a script to extract a sparse tree, selected by
TODO keywords, from my the gtd.org file.  The sparse tree should then
be exported to an html file.  I am using this command:

emacs -batch -l ~/.emacs \
    -eval '(find-file "~/projects/gtd.org")' \
    -eval '(org-show-todo-tree "PROJECT|MAYBE")'  \
    -eval '(org-export-visible ?h nil)'

The resulting html file has entries for "PROJECT" and "NEXT"!
Meanwhile, none of my "MAYBE" entries are selected.  What might I be
doing wrong?