Confused About County DCSS Collection

The child upon whom I pay support turns 18 in late June 2007, so I asked
the county DCSS in California when my last payment is supposed to be,
because I mail 12 post-dated checks from abroad each year, which they cash
each month.

Oddly enough, the county DCSS told me that they have orders not to collect
on my account beyond 1 Feb 2007, and that any money I send to them comes
back to me or goes to arrears (there are no arrears).

That is about 3-4 months before the child turns 18.

What is the deal with this?

I can hardly believe that my monthly support stops short of the child's
18th birthday. Do I send the money instead directly to the child's mother?
Because that's what I am planning on doing.

The last thing I want is for the family law court judge to be summoning me
before his bench asking me why I stopped paying a few months short of the
time of the child reaching majority.

A child is a minor until the 18th b'day in California, right? And the CA
Family Code pretty much says I have to support the "minor" child. Anyone
want to be a lawyer here? Thanks.