Hi, I have following unlang code in the preacct section update request { Calling-Station-Id := "%{%{string:Class}:-%{Calling-Station-Id}}" } If my packet does not contain Class attribut, i expect that Calling-Station-Id will not change. (0) Received Accounting-Request Id 109 from 127.0.0.1:55999 to 127.0.0.1:1813 length 429 (0) NAS-Port-Type = Virtual (0) Framed-Pool = 'BDSLpool' (0) Acct-Input-Octets-64 = 135967391 (0) Called-Station-Id = 'orangenet' (0) Acct-Status-Type = Interim-Update (0) Connect-Info = '1000000000/1000000000' (0) Acct-Output-Packets = 1476063 (0) Framed-IP-Netmask = 255.255.255.255 (0) NAS-IP-Address = 213.151.237.216 (0) Acct-Output-Octets = 1196651182 (0) Qos-Policing-Profile-Name = 'in512K' (0) Acct-Session-Time = 2400 (0) Medium-Type = DSL (0) User-Name = '0200000005@orangenet.sk' (0) NAS-Identifier = 'N-001-BA-BAS-10' (0) Framed-IP-Address = 178.143.0.156 (0) Acct-Input-Packets = 514504 (0) Acct-Output-Octets-64 = 1196651182 (0) Acct-Input-Octets = 135967391 (0) Acct-Session-Id = 'FF10FFFF58000253-4F01A67C' (0) Acct-Output-Gigawords = 0 (0) Service-Type = Framed-User (0) Acct-Update-Reason = AAA-LOAD-ACCT-PERIODIC (0) Acct-Authentic = RADIUS (0) NAS-Port-Id = 'L2TP LNS 595' (0) Qos-Metering-Profile-Name = 'down12288K' (0) Acct-Input-Packets-64 = 514504 (0) Context-Name = 'INET' (0) Calling-Station-Id = '421905000001' (0) Framed-Protocol = PPP (0) Event-Timestamp = 'Jan 2 2012 14:23:41 CET' (0) Acct-Tunnel-Connection = 'LNS1:4945:9576' (0) Acct-Input-Gigawords = 0 (0) Qos-Policy-Queuing = 'pwfq12288K' (0) NAS-Port = 2432696915 (0) Acct-Output-Packets-64 = 1476063 (0) # Executing section preacct from file ../../raddb/auth/sites-enabled/default (0) preacct { (0) [preprocess] = ok ... (0) update request { (0) EXPAND %{%{string:Class}:-%{Calling-Station-Id}} (0) --> (0) Calling-Station-Id := "" ... But Calling-Station-Id is empty. Thank you for help.