SAN Transport Mode not working

Hello,

i have a VMware HA Cluster.
All ESXi 5.5 Servers are connected over 8GB/s FC SAN with Datastores hosted on two Storages (HP EVA and 3PAR 8200).

All Datastores are presented to my both Backup Exec Media Servers (one Central BE Server for Job Management with CASO Option). I am able to see all of my Datatores within my Windows Server 2008 R2 OS.

If I try to do a VM Backup over SAN (EVA or 3PAR) i am getting following Error on both Servers:
Selected Transport Mode not supported.

Any Ideas?

Thanks!
Marco