Cisco ASA – Remote Access VPN not getting reserved address from DHCP

I have configured a Cisco ASA 5520 in an environment where the remote users need to get statically assigned IP addresses. In the past this was done by using MAC address reservations on the DHCP server. In replacing their old firewall and putting in the ASA what I have found is that even though Remote Access VPN is configured to assign IP address’s via the DHCP server and even though that works (You can see the lease on the DHCP server), it does not give them the address that has been reserved by their MAC address. Does anyone know a solution to this? I would love to hear it.