vmrun insufficient permissions

hello everyone

when i try to start a vm using the following command

vmrun -t esx -h https://myserver.com/sdk -u domain\user -p ******* start "[datastore1-mydata] vmname/vmname.vmx"

i get an error  message "Cannot open VM: [datastore1-mydata] vmname/vmname.vmx, Insufficient permissions in the host operating system"

however when i type vmrun -t esx -h https://myserver.com/sdk -u domain\user -p ******* list

i do get a list of all the vms

I have administrator permissions on the said vm and on it's datastore

also, when i try to do the same thing using powercli, it works perfectly, and the VM root user also manages to do this with no problem

i'm guessing it's a permissions thing but what other permissions could i need?

thanks