How to add "create" permission for flexinodes?

My problem: I cannot change the permissions to "Create" and "EDit" flexinode contents via access control. When I click on the boxes and then submit, the ticks simply disappear! I tried doing this for different roles, same results. The only tick that sticks is the one for "administer content types".

I did a search on this and found some old posts, like:
http://drupal.org/node/8350
I'm not really into doing things like patching yet (though i can do some coding). But since that post was in 2004, I assume that by now it should have been patched? Cos I downloaded all my drupal files like just 3 weeks ago.