AppleScript: using the assemble command

[Christian Mittendorf]

Hello!

Can anybody sent me a hint on how to use the assemble command in OG3 
Prof?

I made a group of graphics and copied them as AppleScript. At the end 
of the there is the assemble command.

tell front document of application "OmniGraffle Professional"
	tell page 1
		make new shape at end of graphics with properties {origin: {119, 
195}, size: {78, 57}}
		make new shape at end of graphics with properties {origin: {54, 81}, 
size: {73, 57}}
		assemble graphics -2 through -1
	end tell
end tell

But when I run this script from Script Editor I get an AppleScript 
error complaining about

"OmniGraffle Professional got an error: 
NSReceiversCantHandleCommandScriptError"

and stopping at the "assemble" command.

Any idea?

cu
cm