pci_add auto nic failed on qemu monitor

hello!
execute "qemu-system-x86_64 -M pc -m 256 -hda pc/img.qcow2 -nographic -net nic,vlan=0,macaddr=00:e0:fc:00:00:01 -net tap,vlan=0,ifname=tap0,script=no -serial tcp::3333,server,nowait -boot c"
and then
(qemu) pci_add auto nic vlan=1,macaddr=00:e0:fc:40:20:02
Property 'e1000.netdev' can't take value 'hub0port0', it's in use

the qemu version is 1.4.1

thx!