Membership: errors with popup registration

Hi - I'm getting errors with with "popup registration form" enabled in Membership Page Options

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'membershippublic::popover_sendpayment_form' was given in /home/rightque/public_html/dev.rightquestion.org/wp-includes/plugin.php on line 405

This error appears when I click on signup for a free subscription as a new user.

Any thoughts?