Some interesting info re LACP 802.3ad here:
http://www.ieee802.org/3/hssg/public/apr07/frazier_01_0407.pdf
.
LACP has to be configured on the switch side too. If LACP is not configured on the switch side too, then it will not work properly. Are you sure it is configured on the switch side?
Can you show us the status and configuration of the bond on the appliance? This should show whether 802.3ad has been successfully negotiated with the switch side.
.
802.3ad can be leveraged to provide EtherChannel across multiple LAN switches. EtherChannel has a load balancing algorithm which selects which actual NIC-to-NIC physical links to use... and so what can happen is that most traffic simply lands on one physical link. You'd be unlucky, but it can and does happen. The underlying load balancing algorithm are known as src-mac, dst-mac, src-dst-mac, etc and ip equivalents and mixtures etc. This is usually a switch side configuration setting which affects the entire switch - so be careful. More about that here:
http://www.ciscopress.com/articles/article.asp?p=2348266&seqNum=3
...and here:
http://packetlife.net/blog/2010/jan/18/etherchannel-considerations/
.
If you don't actually yet have 802.3ad configured on the switch side, then you could try "balance-alb" on the Appliance(s), which a lot of people find works just fine.