Stupid 2408mkII /O2r question

[jumpin]

I'm probably missing something really simple but
when I configure a 2408mkII to enable
ADAT banks A and B and plug my O2R's 1st ADAT card
into bank A on the 2408 and the O2R's 2nd ADAT card into bank
B, I can hear the 2408's ADAT outputs through my board's
tape returns
but can't get a signal into the corresponding inputs
to record. However,
If I configure a second 2408 similarly as the first
and use bank B on both 2408's one for the O2R ADAT card
1 and the other (on the second 2408) for the O2R's 2 ADAT card,
everything works fine (as long as my routing on the board
and in DP is correct). I'm not even selecting the ins or outs
corresponding to ADAT card 2 in the 02R or the 2nd 2408 in DP.
I'm dealing only with inputs 1-8 on both the O2R and
the first 2408. Is there something strange about
using ADAT Banks A and B on a single 2408 at the same time
as long as the the 2408s ADAT ins and outs on
Banks A and B are enabled?

Thanks,

Jon