i have instllaed powerchute network shutdown v3.0.0 in esxi4.1

i have installed vma and under this the powerchute program

any vmware ( vma too) are in guest shutdown but when the powerchute try to shutdown virtual machine (  have configured an event for begin shutdown when the apc ups is in battery mode from 120 second) in  the powerchute i view the event start but  no virtuasl machine go in shutdown guest and the program  powerchute crashes ( i must manually restart vma for restart powerchute

what can i do ?

thanks Alberto