VBox screenshots without top/bottom bars ?

Hmm.. I must be missing something. Followed Mrk's tutorial http://www.dedoimedo.com/computers/virtualbox-screenshot.html but am unable capture a screenshot without the bars.
Linux host = SL6.2
Guest = Windows 8 Consumer Preview.
Extensions and Guest additions installed.

Typing VBoxManage controlvm Windows8 CP screenshotpng ~/Desktop/test.png in terminal
I get ..

VBoxManage: error: Could not find a registered machine named 'Windows8'
VBoxManage: error: Details: code VBOX_E_OBJECT_NOT_FOUND (0x80bb0001), component VirtualBox, interface IVirtualBox, callee nsISupports
Context: "FindMachine(Bstr(a->argv[0]).raw(), machine.asOutParam())" at line 97 of file VBoxManageControlVM.cpp

What can I do to get it right ? I am sure I did something really silly.

EDIT:-

Well really ! I stumbled across the test.png in my home folder ! So it appears the error message can be ignored ? No, I made a syntax error. Should be..
VBoxManage controlvm "Windows8 CP" screenshotpng test.png

 

Best use a name without spaces.
Mrk

 

I am so embarrassed, worse than suffering from orphaned inodes

 

The important thing is that my tutorial works
Mrk