Permission: Read Topics and Post New Topics not working together

This is the bug I found when I try to do the Private Forum mode.

When I try to make the forum's topics unviewable by other users in my PhPBB forum, I set the Permission: Read Forum to NO. Then I set the Permission: Can Post New Topics to YES. When I view the forum that has this permission, It Says "You do not have the permission to view the topics in this forum". But I am wandering where is the New Topic button? The Permission: Can Post New Topics - Yes does not work with Permission: Read Forum - No. Is that a bug or really a feature of that permission. If it is a bug, please fix it because I really need It and I know that PhPBB is the best forum that I know...