Conflicting with WP Full Calendar

Basically when I activate WP User Frontend it cancels out my WP Full Calendar making it disappear from my site.

WP USer Frontend
http://wordpress.org/extend/plugins/wp-user-frontend/

WP Full Calendar
http://wordpress.org/extend/plugins/wp-fullcalendar/

anyone have any ideas why this is happening?

I’m no expert but WP Full Calendar pull info from my posts and creates an Ajax calendar based on my posts – could this have something to do with WPUF also creating posts?

thanks

http://wordpress.org/extend/plugins/wp-user-frontend/