Ok. I am trying to use the svmotion plugin but it won't allow me to move another VM. Could be a plugin issue I guess.
The plug-in is just a graphical connection to the official command line, it runs the commands on the server. I know it's not the best option, but just to verify it's not a VC issue, have you tried the command line method? It's not pretty I know, and it's a hassle because it is case sensitive, but if you keep that one vmotion running, and try the NEXT attempt via command line that will provide some clues if it's the plugin or not. I doubt it is the plug-in, there may be a problem with vmotion / vkernel on the other VM you are trying. Give the command line method a try just to see if you get any further.
