The black screen is caused by the OS display being turned off. You are currently unable to connect to a VM that has a disabled display via HD Station (this is a known issue and is being worked on.) For the time being, we advise that you adjust the display setting of your OS.
Please see the below steps for adjusting the display setting in Windows 7.
Right-click on the Windows 7 desktop, choose “Personalize” and click “Screen Saver”.
Click “Change power settings”.
Click “Choose when to turn off the display” on the left panel.
Click “Turn off the display”.
Set it to “Never”.