Console only empty with cursor

I Have installed Turnkey-redmine to an internal-IP (10.0.0.2) on my Proxmox.

I start the vm, and can reach Redmine via proxmox-IP:myport. But if i start console from proxmox-gui for this vm, i got only a black screen inside the popup, which shows me the cursor.
I can press enter or write something, but nothing happend.

How can i fix this, to get access via konsole to this VM?