PoE Wierdness

[ChrisMoran64]

I am completely stumped here, so crying out for help:

My hardware config consists of:

1 x Ether 10 + Freetronics Terminal Shield.
1 x Freetronics Midspan PoE Injector
1 x 9VAC power supply.
1 x NetGear 100Mb/s dumb Ethernet Switch.
1 x 30m Cat5 straight Ethernet cable.

If I remove the PoE jumpers and power the Ether10 via it's onboard socket, it connects to the switch and communicates nicely.
If I use a DLink PoE injector/Receiver pair (with the jumpers still removed) powering the Ether10, everything works
...So the basic hardware seems to work OK, agreed?

However, if I use the MidSpan adapter, AND the PoE jumpers in place on the Ether10, the board powers up and runs, but there is no link status on the switch, so the board can't communicate.

What I've tried
Different Ethernet cables - no change
Different Switches (NetGear, Cisco and DLink 100MB/s) - no change
Different plug-pack power supplies - no change
Replaced the mid-span device - no change

Did I misunderstand something? From the documentation, all I need to do is to put the two PoE jumpers on the Ether10 board into place (as opposed to being open) and it should all work, right? I am getting power so I am confident things are set up right.

I really want to be able to use the PoE capabilities of this board, because it will make the project so much easier than cutting up cables or buying a bunch of individual power connections, but I am getting nowhere.

Any suggestions greatly appreciated.

Thanks,