PostgreSQL user in UCK not existing in target system

Hi there!

I've created a customized Ubuntu 10.04 LiveCD. One of the apps included is PostgreSQL. While configuring the ISO image with UCK I created a PG user, name it "user1".

After I added all packages I compiled the ISO. While configuring the installation of customized ubuntu on a new computer, I selected the name "user1" as the name for the Ubuntu user. At the end, everything worked fine, but there's an application that does not work because it uses PostgreSQL with the user name "user1", and "user1" does not exist as PG user on the target system. If I create it manually again, the app runs correctly.

The question is: why the user I created in PG while configuring the ISO from the UCK console does not longer exist on the target computer? Is it because its name is the same of the Ubuntu user? How could I get my customized ubuntu working with my new PG "user1" without the need of creating it manually after the Ubuntu installation?

Thanks in advance,

Jordi