The simple answer is that it does not compile in Appeon. I am not working with the Appeon piece and I am waiting for a more specific description from the guys that do.
Our version of Wintertree is very old. The dll is dated 1999. Maybe the answer is to just buy the latest version? At their web site they list many flavors of the spellchecker and it is a bit confusing to me. A few days ago I submitted via "contact us" at their website explaining the problem and asking their advice. No response yet. If you can prod something out of them, that would be great.
Beyond that, what are other folks doing for spellcheck that works for both PB and Appeon?