First of all, yaoi, dereyoruk and octopus are not valid tags here. Since there are no posts with those tags, posts with those tags are NOT showing up in your search results...

Secondly, for yuri and tentacles, are you sure the posts you're seeing are tagged with those tags? Some posts may simply be missing the proper tags, or you may be expecting shoujo_ai posts to be tagged yuri.

*Edit: And yaoi is banned here, so if you're seeing posts you think should be tagged yaoi, they are probably just shounen_ai.