What is error -12?

Hello,

after plugging in my 0ace:1215 I get

ds9 ~ # dmesg |grep zd1211
zd1211rw usb_init()
zd1211rw 1-2:1.0: zd_chip_read_mac_addr_fw()
zd1211rw 1-2:1.0: probe() couldn't register device. Error number -12
zd1211rw: probe of 1-2:1.0 failed with error -12
usbcore: registered new interface driver zd1211rw
zd1211rw initialized

What does error -12 mean?

Stefan