Put you old TM6 number.
Unless you are entering with a new visa or changing addresses a TM30 report is no longer required.
Thanks, Do you know why I can't do my 90 day report online? I keep getting rejected and I don't know why. Does the address have to be the same as your TM30? The last 2 times, I had to go in person to do my 90 day report, so their system should have my updated info. I was able to do it on the old system, but every since I got a new passport last October, it hasn't worked. Any suggestions?