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 CCSM SMB Specialist