When getting that message I try to simply ask System Events to list every UI element or entire contents (get entire contents of application process "Adobe Illustrator" of application "System Events", and you can see in the results all the possibilities you have; just Apple-F "extrude & bevel" and you're done, you copy-paste the relevant part back in the code and run.
Hope this helps!
PS: Prior to this, try correcting the line as above as for the last part of it (... of menu bar 1 of application process "Adobe Illustrator" of application "System Events").