Vista - problem using Microsoft.Exchange.Management.PowerShell.Admin from C#

I'm trying this example:

http://knicksmith.blogspot.com/2007/...ents-with.html

I've complied the project for x64 platform and when I attempt to
execute it on an Exchange 2007
server,this line:

PSSnapInInfo info =
rc.AddPSSnapIn("Microsoft.Exchange.Management.PowerShell.Admin", out
warning);

Gives this error:

Unhandled Exception:
System.Management.Automation.Runspaces.PSSnapInException: Cannot load
PSSnapIn Microsoft.Exchange.Management.PowerShell.Admin. Encountered
following error: Unable to cast object of type
'Microsoft.Exchange.Management.PowerShell.AdminPSSnapIn' to type
'System.Management.Automation.CustomPSSnapIn'.

Anyone have any ideas? As the line sed in quitea few examples and
others don't seem to be suffering from, I am assuming that "Unable to
cast object of type" is hiding the real error.