How do I auto generate new student id's beginning with a certain number ?

How can I start all new enrollments at ALL of our schools with an automatically-generated number greater than 600000?

I reset my low/high/laststudentno in the Prefs table to low:600000 high:999999 and lastnum to 600005.

I restarted PS, then verified that the laststudentno was still 600005.

Then when I enrolled a kid, it says "Student Number 10000 is already in use." and it sets the laststudentno back to 10000.

Any ideas would be very much appreciated.

We are using version 6.1.0.1.0102

Thanks!!