[vbox-dev] Problem with usage of SaveState command

[pdufrene.other at free.fr]

Hello,

I am trying to use the COM api and implementing my own front-end

I create a Virtualbox object.
I create a Session object.
I get my machine
I lock the machine



I do session.console.PowerUp()

everything is fine 

Later I call
session.Console.Pause();

progress = session.Console.SaveState();
progress.WaitForCompletion(-1);


the save state generation starts but fails later with following messages in the LOG

00:01:46.033 Changing the VM state from 'RUNNING' to 'SUSPENDING'.
00:01:46.065 PDMR3Suspend: 31 003 929 ns run time
00:01:46.065 Changing the VM state from 'SUSPENDING' to 'SUSPENDED'.
00:01:46.267 Changing the VM state from 'SUSPENDED' to 'SAVING'.
00:01:47.484 SSM: Execute save failed with rc=VERR_INVALID_HANDLE for data unit 'HGCM'/#0.
00:01:47.497 SSM: Failed to save the VM state to 'C:\xxxxxx\Snapshots\2012-04-27T12-30-58-108530900Z.sav' (file deleted): VERR_INVALID_HANDLE
00:01:47.497 Changing the VM state from 'SAVING' to 'SUSPENDED'.

If I do the same with the Virtualbox Gui, the saved states is well generated:
00:00:25.525 Changing the VM state from 'RUNNING' to 'SUSPENDING'.
00:00:25.587 PDMR3Suspend: 61 331 660 ns run time
00:00:25.587 Changing the VM state from 'SUSPENDING' to 'SUSPENDED'.
00:00:42.184 Changing the VM state from 'SUSPENDED' to 'SAVING'.
00:00:43.519 SSM: Footer at 0x56f697c (91187580), 33 directory entries.
00:00:43.522 SSM: Successfully saved the VM state to 'C:\xxxxxx\Snapshots\2012-04-27T12-34-31-010458900Z.sav'
00:00:43.522 Changing the VM state from 'SAVING' to 'SUSPENDED'.
00:00:43.522 Console::powerDown(): A request to power off the VM has been issued (mMachineState=Saving, InUninit=0)
00:00:43.522 VRDP: TCP server closed.
00:00:43.523 Changing the VM state from 'SUSPENDED' to 'POWERING_OFF'.

HGCM stands for Gost Guest Communication Channel I guess, Do I need to do something before requesting for saved state?
thanks in advance.