I am trying to reset the starting SCN number for an Integrated Capture extract. Logically I would like to use the ALTER EXTRACT myextact, BEGIN NOW. But that doesn't seem to work with Integrated Capture. So instead, I capture the current SCN from the database, and ALTER EXTRACT myextract, SCN <99999999>
For example:

But this still doesn't work. When I try to start the extract I get the following error:

What am I doing wrong?
What is the best way to reset an Integrated Capture extract to begin extracting now?
Thanks.