about permissions

Hello, i'm happily using node hierarchy, it is really useful...thank you
But i'm not getting the way the node hierarchy permissions work...
my situation is this:
i've a role with a set of permissions, they can create only some of the content types....quite usual :-)
That nodes can be parent or child or both. If i go creating such of a node, node hierarchy doesn't let me choose between every potential parent.
Just one.

I started thinking what it might mean...nothing convinced me.

And i don't know why but it seems to let that user choose only the ancestor sometimes...sometimes (with other content type) a parent too but not all of the nodes the user could create basing on the content type permissions.

I noticed that i need to give the role the "administer nodes" permission to make that role able to choose among every potential parent (the ones set to be potentially parent).
this is not the way, because it is really too much.

I have the "create child nodes", "edit all node parents", "edit own node parents", "reorder children" permission checked for that role.
I thought the first to be the condition for a user to give a father ,
the second one the chance to change the father of every node,
the third only for the nodes the user owns,
I'm guessing the forth to be the chance to move up and down childrens in a list of childrens.

So, checking the first should be enough to give a user with a role the ability to create child, choosing the node he likes
Isn't strange?
Thanks,
Da.