Pretty much in the title.
vCenter was upgraded back in September or so to 5.1, and there are mixed clusters running: 4.0 esx, 5.0 U1, and 5.1.
On the 4.0 ESX hosts, we do not see the CPU/Host Mem or Guest Mem performance stats. They all show "0".
Screen shot attached.
We've tried restarting the management services. We've also rebooted the hosts. No luck.
Any suggestions are appreciated.