I am get this error when I click the link to read the feedback left by a user. The message is on the ADMIN template parameter. I am getting this on the two rows, discussions and wordpress debug info.
Warning: call_user_func() expects parameter 1 to be a valid callback, function 'un_feedback' not found or invalid function name in C:\xampp\htdocs\mac\wp-admin\includes\template.php on line 927
I have shutdown the comments and discussion as my site is not open for these comments. It is just pages and simple posts to inform the public. I have other modals LOGIN and CONTACT form and your plugin works nicely with them as the look and feel the same. I guess you are using the simple modal JS. Your plugin is complicate for a simple feature but I guess using the word press framework to do the work requires all the code to use the posting functions.
I modified only the CSS to get this to look like the other modal windows.
Is this a normal error? Let me know if this is an ADMIN issue or if we can close down the call to the ADMIN template.php