This could be a problem with the version of the bindings file you have installed. What version of html editor are you using? Have you reinstalled any other extensions since installing html editor?
I think if you update the file located at:
I have attached a zipped version of that file that appears to work properly for me. If that still doesn't work we may need to open a support incident to have an engineer work with you directly.
In the meantime you could also update the code manually to refer to the correct form element name and it should work properly.