MAC address

We are using NAEthTransmit() to send network packets with a NET+50 (and PHY LXT971A) with NET+OS 6.0. Basically this works fine. But the MAC address of the packets are always 00:40:9D:00:00:00 even though we’ve written another address in the m struct. Also defining APP_BSP_MAC_ADDRESS in our appconf.h doesn’t help. How can we change the MAC address??? Regards, Dave Buechi