vmrun responds with "Error: Unknown Error"

Hello,

OS: CentOS 6 x86_64, VMWare Server 2 of the latest known version. Everything works just fine when controlled via Web interface.

I am trying to do batch VM stop/start to have its files backed up. To stop VM, I run (as root) from SSH shell at the same server where VMWare Server is running a command like this:

vmrun -T server -h https://server:8333 -u vmroot -p 'vmpass' stop /full/path/to/server.vmx

All I see is "Error: Unknown Error". Not too informative, I must add.

When the host URL is used with the same name/password, it works fine.

Could someone suggest ways to overcome this error? Thanks.