Signup Code for blog creation

Hi,

I am trying to modify your Signup Code plugin to validate a password for Blog creation instead of User signup and I have modified the required lines in the plugin as per https://premium.wpmudev.org/forums/topic/forcing-signup-code-for-all-users but although it now appears on the blog creation page it doesn't seem to matter whether you leave it blank or enter the incorrect password. Any ideas what may be wrong? I am running WPMU 3.1.3 and the latest version of the signup code plugin.