Queue Tree is not working properly!

To achieve the business goal I have implemented this (only related lines exported).

3 types of users having priorities low, med, high. When parent queue is full it should drop packets from low to high priority, and if I set max limit to 10M it must limit it’s child to use maximum of 10mbps.
But it’s not working like that if usage is about 40mbps and i changed queue max limit to 5M it still remains to 30,35M why it is so. Please explain if i am wrong max limit,Limit at etc.

RB1100AHx2, ver 6.40.8


/interface list member
add interface=ether1 list=WANS
add interface=ether2 list=WANS
add interface=ether3 list=WANS
add interface=ether4 list=WANS

/ip firewall mangle
add action=mark-routing chain=prerouting comment=\
    "corporate policy based routing" disabled=yes dst-address-type=!local \
    new-routing-mark=CORP-MARK passthrough=yes src-address=\
    172.16.8.1-172.16.11.254
add action=mark-connection chain=forward comment="QOS Corporate" \
    new-connection-mark="Qos Corporate con" passthrough=yes src-address=\
    172.16.8.1-172.16.11.254
add action=mark-packet chain=forward comment=in connection-mark=\
    "Qos Corporate con" in-interface-list=WANS new-packet-mark=\
    "Qos corporate_pkts_in" passthrough=no
add action=mark-packet chain=forward comment=out connection-mark=\
    "Qos Corporate con" new-packet-mark="Qos corporate_pkts_out" passthrough=\
    no
add action=mark-connection chain=forward comment="QOS Businesses" \
    new-connection-mark="Qos Business con" passthrough=yes src-address=\
    172.16.4.1-172.16.7.254
add action=mark-packet chain=forward comment=in connection-mark=\
    "Qos Business con" in-interface-list=WANS new-packet-mark=\
    "Qos business_pkts_in" passthrough=no
add action=mark-packet chain=forward comment=out connection-mark=\
    "Qos Business con" new-packet-mark="Qos business_pkts_out" passthrough=no
add action=mark-connection chain=forward comment="QOS HOMES" \
    new-connection-mark="Qos Homes con" passthrough=yes src-address=\
    172.16.0.1-172.16.3.254
add action=mark-packet chain=forward comment=in connection-mark=\
    "Qos Homes con" in-interface-list=WANS new-packet-mark="Qos home_pkts_in" \
    passthrough=no
add action=mark-packet chain=forward comment=out connection-mark=\
    "Qos Homes con" new-packet-mark="Qos home_pkts_out" passthrough=no



/queue tree
add burst-limit=100M burst-threshold=35M burst-time=5s comment="30m 5sec" \
    max-limit=47M name=1-QOS-IN parent=global priority=4 queue=default
add limit-at=6M max-limit=15M name="PRIO 1 - Corp" packet-mark=\
    "Qos corporate_pkts_in" parent=1-QOS-IN priority=1 queue=default
add limit-at=10M max-limit=18M name="PRIO 2 - Business" packet-mark=\
    "Qos business_pkts_in" parent=1-QOS-IN priority=2 queue=default
add bucket-size=0.3 burst-limit=42M burst-threshold=25M burst-time=10s \
    limit-at=10M max-limit=35M name="PRIO 3 - Homes" packet-mark=\
    "Qos home_pkts_in" parent=1-QOS-IN priority=3 queue=default
add max-limit=25M name=1-QOS-OUT parent=global queue=default
add name="PRIO 1 - Corp-O" packet-mark="Qos corporate_pkts_out" parent=\
    1-QOS-OUT priority=1 queue=default
add name="PRIO 2 - Business-O" packet-mark="Qos business_pkts_out" parent=\
    1-QOS-OUT priority=2 queue=default
add name="PRIO 3 - Homes-O" packet-mark="Qos home_pkts_out" parent=1-QOS-OUT \
    priority=3 queue=default