Memovie: error with JComments

I installed new template also in a base joomla 1.5.15 installation. I created some sections and categories and items in main menu, but in every page there is this error:

Notice: Undefined variable: userID in ...templatesgk_memovielayoutsblocksusertoolsregister.php on line 19

Then when I install JComments other errors there are more errors in every page:

Notice: Undefined property: ContentViewSection::$article in ...templatesgk_memoviehtmlcom_contentsectionblog_item.php on line 125

Notice: Trying to get property of non-object in ...templatesgk_memoviehtmlcom_contentsectionblog_item.php on line 125

Why?