This site is being deprecated.
Please see the official X‑Plane Support page for help.
Are you having this problem with a custom aircraft or are you trying to modify one of the default aircraft? IIRC, the default aircraft panels are now all drawn via plugin and cannot be edited in Plane Maker.
For better help with a custom aircraft design, I'd recommend the X-Plane.org developer forum.
This site is no longer being actively maintained.