ERROR: invalid input syntax for integer: ""

Hi all,
I get invalid input syntax when UPDATEing my radacct table:

freedsl=# \d radacct
Table "public.radacct"
Column | Type | Modifiers
----------------------+--------------------------+-------------------------------------------------------------
radacctid | bigint | not null default nextval('radacct_radacctid_seq'::regclass)
acctsessionid | character varying(32) | not null
acctuniqueid | character varying(32) | not null
username | character varying(253) |
groupname | character varying(253) |
realm | character varying(64) |
nasipaddress | inet | not null
nasportid | character varying(15) |
nasporttype | character varying(32) |
acctstarttime | timestamp with time zone |
acctstoptime | timestamp with time zone |
acctsessiontime | bigint |
acctauthentic | character varying(32) |
connectinfo_start | character varying(50) |
connectinfo_stop | character varying(50) |
acctinputoctets | bigint |
acctoutputoctets | bigint |
calledstationid | character varying(50) |
callingstationid | character varying(50) |
acctterminatecause | character varying(32) |
servicetype | character varying(32) |
xascendsessionsvrkey | character varying(10) |
framedprotocol | character varying(32) |
framedipaddress | inet |
acctstartdelay | integer |
acctstopdelay | integer |
Indexes:
"radacct_pkey" PRIMARY KEY, btree (radacctid)

The query is:

UPDATE radacct
SET
AcctStopTime = ('2009-09-25 10:35:44'::timestamp - '0'::interval),
AcctSessionTime = CASE WHEN '' = '' THEN (EXTRACT(EPOCH FROM ('2009-09-25 10:35:44'::TIMESTAMP WITH TIME ZONE - AcctStartTime::TIMESTAMP WITH TIME ZONE - '0'::INTERVAL)))::BIGINT ELSE '' END,
AcctInputOctets = (('0'::bigint << 32) + '0'::bigint),
AcctOutputOctets = (('0'::bigint << 32) + '0'::bigint),
AcctTerminateCause = '',
AcctStopDelay = 0,
FramedIPAddress = NULLIF('', '')::inet,
ConnectInfo_stop = ''
WHERE AcctSessionId = ''
AND UserName = 'mihamina'
AND NASIPAddress = '0.0.0.0'
AND AcctStopTime IS NULL

I cannot find the problem....
Any hints?
Thank you.

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