I have a logon script that does the same thing, printers based off of OU membership.

I use the incontainer() UFD. Dont forget this udf needs the TranslateName() too.

Here is just a SMALL snip of our 35 site logon script that maps printers.

 Code:
;Use the OU to dertermin what Site for printers and icons.
$Offices = 'ou=Offices,ou=STD,dc=elements,DC=std'

$dfw 		= ',ou=dfw,'		+$Offices
$abrams 	= 'ou=abrams'		+$dfw
$berry 		= 'ou=berry'		+$dfw

Select

	;------------Dallas------------

	case incontainer($abrams,'user')[0]
		? 'Abrams'
		$ = addprinterconnection('\\st-ps01\Copier Abrams')
		$ = setdefaultprinter('\\st-ps01\Copier Abrams')

	case incontainer($berry,'user')[0]
		? 'Berry'
		$ = addprinterconnection('\\st-ps01\Copier Berry')
		$ = setdefaultprinter('\\st-ps01\Copier Berry')


endselect