zyspec no problem, it is already so nice to you to take the time to solve the bugs of this module
So, this bug is solved with your 2.22 beta1 version.
There are still these bugs/problem to solve:
https://github.com/XoopsModules25x/apcal/issues/8
https://github.com/XoopsModules25x/apcal/issues/9
https://github.com/XoopsModules25x/apcal/issues/10
https://github.com/XoopsModules25x/apcal/issues/11
Thanks!