Enable EasyCalcCheck spam protection persists

Joomla 1.5.26
Easybook Reloaded Version: 2.0.8.1
EasyCalcCheck PLUS 1.5-14-1

Hi,

I know I'm using an old joomla but rebuilding the whole site in 2.5 for this one issue is overkill, esp. since I do it for free

example of problem

from the above example you can see the re-captcha is working perfectly, but the small arithmetic question persists. I have disabled "Enable EasyCalcCheck spam protection" in EBR with no effect.

Have you come across this before?

A much older version of Easybook is still installed and I have left it there as I don't know if uninstalling it will remove all the guestbook entries.

Thanks for the great guestbook and spam protection.