Cant post comment on a task.

When I view a created task, and try to post comment, I get the following exception message.

[6] create categories
Start date: Tuesday, September 20
Due date: Tuesday, September 20
Edit | Delete | Mark task as completed
exception 'Exception' with message 'Call to undefined method DataObject::hasAvatar()' in /home/five12/sites/projects/environment/classes/dataaccess/DataObject.class.php:1249 Stack trace: #0 /home/five12/sites/projects/application/views/comment/object_comments.php(21): DataObject->__call('hasAvatar', Array) #1 /home/five12/sites/projects/application/views/comment/object_comments.php(21): User->hasAvatar() #2 /home/five12/sites/projects/environment/classes/template/Template.class.php(77): include('/home/five12/si...') #3 /home/five12/sites/projects/environment/classes/template/Template.class.php(48): Template->includeTemplate('/home/five12/si...') #4 /home/five12/sites/projects/environment/classes/template/template.php(35): Template->fetch('/home/five12/si...') #5 /home/five12/sites/projects/application/helpers/application.php(493): tpl_fetch('/home/five12/si...') #6 /home/five12/sites/projects/application/views/task/view_task.php(57): render_object_comments(Object(ProjectTask), '/index.php?c=ta...') #7 /home/five12/sites/projects/environment/classes/template/Template.class.php(77): include('/home/five12/si...') #8 /home/five12/sites/projects/environment/classes/template/Template.class.php(48): Template->includeTemplate('/home/five12/si...') #9 /home/five12/sites/projects/environment/classes/template/template.php(35): Template->fetch('/home/five12/si...') #10 /home/five12/sites/projects/environment/classes/controller/PageController.class.php(107): tpl_fetch('/home/five12/si...') #11 /home/five12/sites/projects/environment/classes/controller/PageController.class.php(72): PageController->render() #12 /home/five12/sites/projects/environment/classes/Env.class.php(131): PageController->execute('view_task') #13 /home/five12/sites/projects/init.php(189): Env::executeAction('task', 'view_task') #14 /home/five12/sites/projects/index.php(11): require('/home/five12/si...') #15 {main}