Raid setup with LianLi EX50 and MAC PRO

hi there,
having decided to go for an external raid system I've found the Lian LI EX-50 which houses up to 5 drives.
I've put 2 seagate barr. 1.5 TB and 2 seagate barr. 1.0 TB in and now the trouble starts.
when I power it up, it shows all four drives mounting( green lights) for like 10 sec.
then with a short blink of red 3 of them go out and one stays on.
this is the one that mounts on the desktop.
the others dont show up at all.this is all independent from the config of the toggleswitches in the back.
I'm on an OWC internal ESATA adapter and my other ESATA disks that I occasionally connect through that all work perfectly fine.
also the software that comes with the EX50 (JMraid setup) says <no drives or raids found>.
could it be that I need a port multiplier or something like that? is it a mac problem ?
any Ideas ?
cheers
stephan