vCenter 5.5, RHEL 6 and ESXi 5.1

Hi,

I have an issue connecting to ESXi hosts. I have two ESXi 5.1 hosts and installed some RHEL 6 on that. I installed vCenter 5.5 to manage.

I can connect to host and can manage all RHEL 6 VMs without any issue.

When I add those hosts to vCenter5.5, I can connect without any issue, but when I power on RHEL vm, the host automatically and straight away disconnect and cannot manage anymore.

Is the compatibility issue? between RHEL6 and vCenter 5.5? or anything else?

Really appreciate for any help.

Thanks

Thu Ya