I want to shape the trafic on my router for my network

I decided to use tc qdisc but I receive the following error, and I don't know where I am wrong.

If I try any of these commands:

"tc qdisc del dev eth0 root

tc qdisc show dev eth0

tc qdisc add dev eth0 root handle 10: cbq bandwidth 10mbit avpkt 1000"

I receive the following error:

"RTNETLINK answers: Invalid argument
Dump terminated"

The problem is about eth0 which is not recognized but i don't understand why. If I type ifconfig all is fine, the internet is working well. Should I have to do something with the device?

I think it's something simple but, I'm missing it.

Please help!

Thanks in advance!!!

P.S. I use Debian 2.4.18 bf 24, Iptables v1.2.11