IDE compact flash reader FAILURE message

This is not a big issue in CURRENT, or is even much of a priority I
feel, but I thought I'd ask about it anyway.

I have a compact flash reader inserted into the IDE port on my
motherboard. It can host two compact flash cards. Currently I have an
8GB 133x compact flash and an 8GB 266x compact flash (both Transcend) in
the slots.

What I find interesting is that the 8GB 266x compact flash appears in
dmesg as such:-

ad5: FAILURE - SET_MULTI status=51 <READY,DSC,ERROR> error=4 <ABORTED>
ad5: 7775MB <TRANSCEND20070418> at ata2-slave UDMA66

It seems like I can write to it anyway, but I haven't tried yet.
What's the reason for the FAILURE? I assume it has something to do with
the faster write speed on the card.