nice menu will not show up

im using the pixture reloaded theme on a fresh drupal install. i put a nice menu block for the navigation menu in the superfish menu region and it shows up fine. when i added a page that had a menu item in primary links, my nice menu disappeared completely. so i went to themes configuration for pixture and unchecked primary links, and my navigation menu showed up again. when i changed the menu source to primary links from navigation, the nice menu disappeared again. and when i changed the menu source back to navigation, it won't even reappear. the block is still present from site building but nothing will show up. is this a bug or what?