Merge Replication with filters throwing error

I'm synchronizing SQL Mobile 2005 with SQL Server 2005 using Merge
Replication. I've filtered a table like this:
WHERE HOST_NAME() = convert(nvarchar(100), patientId)
"patientId" is uniqueidentifier type column, the primary key of
"Patient" table.
The error when synchronizing is the following:
"The row operation cannot be reapplied due to an integrity violation.
Check the Publication filter. [ Table = Appointment,Operation =
Insert/Update,RowGuid = {F64E1023-01AD-DA11-8ED9-0004E2B45615} ]}"
Table Patient is joined with table Appointment but I don't understand
the error.
I think this sentence worked in SQL Server 2000 and SQL Server E 2.0.
I would appreciate any help on this.
Regards.
I've also tried same filter for Appointment database, and here I don't
receive any error, but the filtering is not correctly done.
Can anybody tell me if the following filtering is correct: WHERE
HOST_NAME() = convert(nvarchar(100), patientId)
Be sure this filtering has correctly worked in the past.
Any ideas please?
Regards.