Get on the switch and find out the status of the port the Evoko is patched to.
Is it up?
What is its PoE status?
What speed has it negotiated?
What is spanning tree doing?
WHat are the switchport traffic and error statistics?
Check the switch log (change it to log info/debug first), and observe the switch logging events when you patch in the Evoko.
What is it doing when you patch it in?
In the event that auto-negotiation is failing and/or there are errors on the port, change the switchport to 100/Full duplex instead of Auto, and see if anything change.
(Remember to set it back to Auto after testing this).