Recently faced an error to install port in freebsd 9.0, the reason for this type of error is due to freebsd support for older version is no longer there. below is the screen shot of the error:
“unknown modifier ‘t’ freebsd ports”
to overcome this I updated freebsd 9.0 to 9.1 and then installed the ports easily.
root@freebsd:/root#freebsd-update upgrade -r 9.1-RELEASE
(to update release from 9.0 to 9.1)
(to install the update)
then reboot the server and run the above command again
root@freebsd:/root#portsnap fetch update
(to update the ports)
then you can install the desired ports without any error!
HOPE it works for you as well !