Timestamp issue

Hi
I have copied all files and folders in /home directory from one linux server to another. For this purpose i used rsync as follows:
rsync -avr /home/abc root@xx.xx.xx.xx:/home and this copied all the files and folders to the new server. But later on after a day i realized that the files are copied but their modification date and time has changed for all. For all files and folder it was showing the date and time when they were copied and their original timestamp was not there. Then i went back to the old server and tried this :
rsync -avr -t -u /home/abc root@xx.xx.xx.xx:/home but nothing happened. I used -t to preserve timestamp during transfer and -u to not overwrite the modified files. Can anyone plz help
Thanks in advance.