ADS multicast image deployment

[mrmovie]

I would if anyone would be so kind to give me some advice.
I am working on Server2003 deployments with Automated Deployment Services. It is all going rather well.
I can deploy a base OS using a SYSPREP image to a bare metal box in about 13 minutes! nice.
The documentation says

Support for multicast deployments = Yes

Number of concurrent deployments per server
Up to 128 (multicast). Deployment speed not affected by number of concurrent deployments per server.

For me I thought this meant i could deploy the same image to 10 machines and they all be downloading the image at the same time. However what i find is that each machine must wait its turn to deploy the image!!!
The Image service is set to multicast in the GUI

 

[mrmovie]

interestingly if i run

adsdevice /edit server_name /ids /setvar imagerestoremulticast 1

it returns an error saying this cant be set,

 

[mrmovie]

M$ docs are incorrect it is imgrestoremulticast
their docs are also crap, no where does it say multicast only works if you run your deployment against a set rather than a group or individual machines