Exec-PHP disables p01-contact?

[Belletage]

hi,
(me again, sorry)

I need Exec-PHP (http://get-simple.info/extend/plugin/exec-php/17/) for the Guestbook (http://get-simple.info/extend/a/cumbe), but I recognize, that my contact form p01-contact (http://get-simple.info/extend/plugin/p01-contact/35/) is gone and redused to the string (% contact : name, email!, subject, message! %), after activating Exec-PHP.
[GS3.1.2, Exec-PHP1.1, p01-contact0.9.1]

regards,
Hope