Prison server -Help needed-

Hello, i am currently making a prison server. :D

But something won't work for me. D:

I am trying to create different blocks such as CBAE, but i need to be able to block groups from other groups blocks.

So say C wouldn't be able to access B block, but B block would be able to access C block, and so on.

But i'm not sure if im doing something wrong here, this is an example of what i do:

/region define B-Door

/region flag B-Door entry deny

/region addowner B-Door g:B-Prisoner

It won't let the C-Prisoner groups enter! (Which is good)

But it won't let the B-Prisoner groups enter either! (which is bad)

I don't know if i have explained this well, but if you could help me i would appreciete it loads!