Simple queue Problem

I’m using only simple queue to shape traffic. But when i add a sub under a parent queue the whole queuing system fails.
Like:
“/que sim add name=512kbps target-address=192.168.0.100/29 max-limit=128k/512k limit-at=64k/200k interface=all” works fine.

But when i add another simple rule like

“/que sim add name=P2P target-address=192.168.0.101/32 p2p=all_p2p max-limit=64k/128k interface=all parent=512kbps”

then nothing works, neither the parent nor child. Every thing is unlimited. Why so?