LARTC - Jan 2001 - ingress DSCP marking

I want to set the DSCP at the ingress of the router. 
I tried the following:

    iptables -A OUTPUT -t mangle -d 10.10.10.12 -j MARK --set-mark 1
    tc qdisc add dev eth0 handle ffff:0 ingress dsmark indices 64 set_tc_index
    tc class change dev eth0 classid ffff:1 dsmark mask 0x3 value 0xb8
    tc filter add dev eth0 parent ffff:1 protocol ip prio 1 handle 1 fw
classid ffff:1

But the DSCP value isn''t set correctly. 
What''s wrong with it? If I try to mark the packets at the outgoing
interface then the
DSCP value is set. Why doesn''t it work at the ingress?

Tom Aernoudt