Ovencm extension problem

i downloaded ovencms extension from:

http://www.yiiframework.com/extension/ovencms/

and i have this error during installation:

"Trying to get property of non-object"

it’s occurs on line 321:

C:\server\htdocs\yii\ovencms_release\protected\models\Section.php(321)

321 return $section->id;

can anyone tell me how to install this extension step by step??