if_bridge - what i do wrong

[Wojciech Puchar]

[root at wojtek ~]# ifconfig bridge0 addm tap0
ifconfig: BRDGADD tap0: Invalid argument
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

why?

[root at wojtek ~]# ifconfig bridge0
bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         inet6 2001:XXXX:XXXX:XXXX::1 prefixlen 64
         inet 10.255.245.1 netmask 0xffffff00 broadcast 10.255.245.255
         ether 5a:81:5a:a6:e6:38
         priority 32768 hellotime 2 fwddelay 15 maxage 20
[root at wojtek ~]# ifconfig tap0
tap0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         inet6 fe80::2bd:2cff:fe1d:0%tap0 prefixlen 64 scopeid 0x3
         ether 00:bd:2c:1d:00:00