The problem is the “emc_isilion_power” check. What version do you used before the update to 1.6.0p19?
If it was a 1.6 version also before then it is strange as this check was not changed since two years.
One thing you can try is to disable the “emc_isilion_power” check with the rule “Disabled checks”.
Try then to do a complete reinventory on the machine with “cmk --debug -vvII ISILION-A”
If there are other problems you will get the error message.