Basic relationship problem

I have the following attributes:

Main.OwnerSuburb type Suburb
Main.JobSuburb type Suburb

I can enter these into fields. But when I switch to another form section, or Create or Save:

Main.OwnerSuburb is still there
Main.JobSuburb has disappeared!!!

I tried adding:

Main.Suburbs type Suburb
Suburb.Suburbs type Main

But it makes no difference and I have totally run out of ideas.

What basic thing am I doing wrong??

G,
If you are using multiple form or form sections be sure to add the attribute to each form or section

Christopher

Thanks Chris. This turns out to be part of some other difficulties I have which Tom is helping me with.