After dm6467 mac address changes, the network connection fails, why?

I use three methods to modify the mac address：

1, using commands: ifconfig eth0 hw ether 11:22:33:44:55:66 .

2, I put the mac address into the startup parameters bootargs.

3,  the kernel get mac address  where to set a fixed mac.

These methods will not work, really can not figure out where the problem is.By either method as long as the above, the mac address modified the original mac address, the network through.thanks！