File date/time not preserved on upload

Here is the Transfer Queue log (I had to enable logging to find it):

[2008-05-30T21:05:46] Log opened
[2008-05-30T21:05:46] Initializing. Transfer Queue v1.0.9.13.
[2008-05-30T21:05:46] Resolving host name "xxx.phpwebhosting.com"
[2008-05-30T21:05:46] Connecting to xxx Port: xxx
[2008-05-30T21:05:46] Connected to xxx.phpwebhosting.com.
[2008-05-30T21:05:46] 220-FTP server ready.
[2008-05-30T21:05:46] 220 This is a private system - No anonymous login
[2008-05-30T21:05:46] USER xxx
[2008-05-30T21:05:46] 331 User xxx OK. Password required
[2008-05-30T21:05:46] PASS (hidden)
[2008-05-30T21:05:46] 230-User xxx has group access to: xxx
[2008-05-30T21:05:46] 230 OK. Current restricted directory is /
[2008-05-30T21:05:46] SYST
[2008-05-30T21:05:46] 215 UNIX Type: L8
[2008-05-30T21:05:46] Detected Server Type: UNIX
[2008-05-30T21:05:46] FEAT
[2008-05-30T21:05:46] 211-Extensions supported:
[2008-05-30T21:05:46] EPRT
[2008-05-30T21:05:46] IDLE
[2008-05-30T21:05:46] MDTM
[2008-05-30T21:05:46] SIZE
[2008-05-30T21:05:46] REST STREAM
[2008-05-30T21:05:46] MLST type*;size*;sizd*;modify*;UNIX.mode*;UNIX.uid*;UNIX.gid*;unique*;
[2008-05-30T21:05:46] MLSD
[2008-05-30T21:05:46] ESTP
[2008-05-30T21:05:46] PASV
[2008-05-30T21:05:46] EPSV
[2008-05-30T21:05:46] SPSV
[2008-05-30T21:05:46] ESTA
[2008-05-30T21:05:46] 211 End.
[2008-05-30T21:05:46] Detected Server Software: PureFTPd
[2008-05-30T21:05:46] PWD
[2008-05-30T21:05:46] 257 "/" is your current location
[2008-05-30T21:05:46] CWD xxx
[2008-05-30T21:05:47] 250 OK. Current directory is xxx
[2008-05-30T21:05:47] PWD
[2008-05-30T21:05:47] 257 "xxx" is your current location
[2008-05-30T21:05:47] TYPE I
[2008-05-30T21:05:47] 200 TYPE is now 8-bit binary
[2008-05-30T21:05:47] PASV
[2008-05-30T21:05:47] 227 Entering Passive Mode (xxx)
[2008-05-30T21:05:47] Opening data connection to xxx Port: xxx
[2008-05-30T21:05:47] STOR Header.jpg
[2008-05-30T21:05:47] 150 Accepted data connection
[2008-05-30T21:05:47] 34884 bytes transferred. (168 KB/s) (202 ms)
[2008-05-30T21:05:47] 226-File successfully transferred
[2008-05-30T21:05:47] 226 0.402 seconds (measured here), 84.84 Kbytes per second
[2008-05-30T21:05:47] MDTM 20080416050000 Header.jpg
[2008-05-30T21:05:48] 550 Can't check for file existence
[2008-05-30T21:05:48] MFMT 20080416050000 Header.jpg
[2008-05-30T21:05:48] 500 Unknown command
[2008-05-30T21:05:48] SITE UTIME Header.jpg 20080416050000 20080416050000 20080416050000 UTC
[2008-05-30T21:05:48] 500 SITE UTIME is an unknown extension
[2008-05-30T21:05:48] SITE UTIME 20080416050000 Header.jpg
[2008-05-30T21:05:48] 500 SITE UTIME is an unknown extension
[2008-05-30T21:05:48] MLST Header.jpg
[2008-05-30T21:05:48] 250-Begin
[2008-05-30T21:05:48] type=file;size=34884;modify=20080531010523;UNIX.mode=0644;UNIX.uid=520;UNIX.gid=
520;unique=803gd3805c; Header.jpg
[2008-05-30T21:05:48] 250 End.
[2008-05-30T21:05:48] Log closed

From the 2nd log you can see that your server doesn't offer a feature to set the date/time of a remote file.

Regards,
Mat