[Plugin: WP User Frontend] Conflict with User Access Manager

When trying to activate WP User Frontend when I have User Access Manager already installed, I get an Call to undefined function get_userdata() error. I can solve it by require one pluggable.php but that slows everything down. Do you have any suggestions as to how to have both pluggins working together?

http://ww.wp.xz.cn/extend/plugins/wp-user-frontend/