First, $FWDIR/conf/ipassignment.conf is checked for the user name - can you see in SVTracker the User log in with that name ? This has worked as long as i can think of CP products...
The main ressource (apart from RA VPN Admin Guide) is sk33422 Office Mode IP and ipassignment.conf file; an addition can be found in sk116415 Machine Authentication IP assignment using ipassignment.conf not working. Possible pitfalls can be found in sk116603 and sk105162 (depending also on version).
CCSE / CCTE / CCME / CCSM Elite / SMB Specialist