Do they ask from wood?
Rashi, Targum Yonasan: They ask from an image of wood. Malbim ? refer to 4:12:2:3.
What does the staff tell him?
Rashi: He heeds what Nevi'im of the Ba'al say in the name of idolatry.
Radak: This is like a blind person ? his staff shows him which path to go on. His staff is the false Nevi'im; so my father explained.
Malbim: The wooden image does not answer. A different wood answers ? the staff prepared to strike them. I.e. via their punishment they know that Ru'ach Zenunim (Lust for Zenus} caused them to stray from the path [and serve idolatry].
What is "Ru'ach Zenunim"?
Radak: It is Ru'ach of false Nevi'im ? the spirit of Zenus from under their G-d, like a Zonah is Mezanah under her husband.
Malbim (14): Lust for Zenus.