Channel Bonding

[beowulf]

 Hi everybody

 I am trying to configure channel bonding with Slackware (kernel 2.2.17),
 and a 3com nic (905b) but when I use ifenslave I receive the following
 message:
 
 The interface eth0 is up, shutting it down it to enslave it.
 SIOCSIFSLAVE: Invalid argument.
 
 I tried ifenslave using the old way:
 
 ifenslave eth1 eth0
 
 and the new way
 
 ifconfig bond0 address netmask xxx.xxx.xxx.xxx broadcast xxx.xxx.xxx.xxx up
 ifenslave bond0 eth0
 ifenslave bond0 eth1
 
 Please someone can help me?
 
 Thanks for your attention
 Ricardo