Merge Replication with FTP (Pull)

Hello,

I'm currently testing Merge replicaiton.

I need to have at least one Subscriber wich do not have TCP/IP port open for it's SQL Server Instance.

I have configured my Publisher to deploy snaphot in a ftp. But my Pull Subscriber can't get the initial snapshot (with the DB schema).

On the Publisher Replication Monitor I have these error:

Error messages:
The schema script '' could not be propagated to the subscriber. 
(Source: MSSQL_REPL, Error number: MSSQL_REPL-2147201001)
Get help: http://help/MSSQL_REPL-2147201001
The process could not connect to FTP site 'ftp.XXXX.XX' using port 21. 
(Source: MSSQL_REPL, Error number: MSSQL_REPL20032)
Get help: http://help/MSSQL_REPL20032
220 Microsoft FTP Service
550 No such host is known.  
(Source: MSSQL_REPL, Error number: MSSQL_REPL12003)
Get help: http://help/MSSQL_REPL12003

I can't see where the error is

(I have configure an other Subscriber (in Push) with port open which work perfectly)

Thanks for you help