No files/folders listed after connection

[tjmbct]

After appearing to successfully connect to an FTP server, there are no subdirectories or files listed. When I connect to the server using Filezilla, four subdirectories are listed. Any ideas as to why? I've had a similar issue with SFTP before where the data port was being blocked. Possibly something similar going on here? I see that it isn't using port 20 to transfer data, but why does Filezilla work fine?

[R] Connecting to ##### - Invoices -> IP=##.##.##.## PORT=21
[R] Connected to ##### - Invoices
[R] 220 Welcome to ##### FTP server
[R] USER ######
[R] 331 Password required for ######.
[R] PASS (hidden)
[R] 230 User ###### logged in.
[R] SYST
[R] 215 UNIX Type: L8 Internet Component Suite
[R] FEAT
[R] 211-Extensions supported:
[R] HOST
[R] SIZE
[R] REST STREAM
[R] MDTM
[R] MDTM YYYYMMDDHHMMSS[+-TZ] filename
[R] MLST size*;type*;perm*;create*;modify*;
[R] MFMT
[R] MD5
[R] XCRC "filename" start end
[R] XMD5 "filename" start end
[R] CLNT
[R] SITE INDEX;ZONE;MSG;EXEC;PSWD
[R] COMB
[R] MODE Z
[R] UTF8
[R] LANG EN*
[R] OPTS MODE;UTF8;
[R] 211 END
[R] CLNT FlashFXP 5.4.0.3970
[R] 200 Noted OK.
[R] OPTS UTF8 ON
[R] 200 UTF8 ON Ok.
[R] PWD
[R] 257 "/" is current directory.
[R] CWD /
[R] 250 CWD command successful. "/" is current directory.
[R] PWD
[R] 257 "/" is current directory.
[R] MODE Z
[R] 200 MODE Z Ok
[R] PASV
[R] 227 Entering Passive Mode (######,4,230).
[R] Opening data connection IP: ###### PORT: 1254
[R] MLSD
[R] 150 Opening data connection for directory list.
[R] 226 File sent ok compressed size 100bytes, uncompressed size 300bytes
[R] List Complete: 0 bytes in 0.38 seconds (0.0 KB/s)
[R] PASV
[R] 227 Entering Passive Mode (######,4,231).
[R] Opening data connection IP: ###### PORT: 1255
[R] MLSD
[R] 150 Opening data connection for directory list.
[R] 226 File sent ok compressed size 100bytes, uncompressed size 300bytes
[R] List Complete: 292 bytes in 0.45 seconds (0.3 KB/s)