remotely Powering on physical PC's

We've got physical desktop PC's configured for remote access. If a desktop is powered off the user gets a message that the computer is being powered on. In the task list in the managment console I can see that a "Power On" task is failing. If I manually start a "Wake Up" task (The Power On task is not selectable) the computer will start and the user can connect. Our vWorkspace version is 7.6.