How do you change a fields TYPE and SIZE values

I have an existing database that when opened needs to be automatically updated to reflect all the new field types and sizes from the new database. I have the routine built into my VB app that searches for any NEW fields and adds them to the old database.. but I am having a hard time getting the program to update the type and size of old fields that may have changed.
For instance.. what used to be just a text field now needs more than 255 characters of text.. so has to be changed to a memo field. How would I do this??
every time I try to change the type.. I get an invalid operation error.
Also note that the database does have data in it.
Thanks
Joe

that type of operation is just not allowed with existing fields

the work around is to recreate the whole database as a separate file

then delete the old DB and name the new tmp as old

I could be mistaken, but I do think you can do this now with access2000. Anyone else heard of this?

btw.. thanks for the answer.. you confirmed my fears