Selecting, not focusing a project or a task in a specific perspective?

How can I select, not focus a project or a task in a specific perspective using AppleScript?

I tried to hack together the following but it doesn’t work

tell application "OmniFocus"
tell front document
	tell sidebar of document window 1
		set selected trees of sidebar to project whose id is "lkjh"
	end tell
end tell
end tell

Any help would be appreciated.

Regards,

Jhn