I have added a new field called dept.name to the interactions form, it is linked to the contacts table which has a field called dept.name.
When I click on the fill button on the form to select a deptartment from the list, it brings back a list of the contact name, phone number, as well as the deptartment name which is the only field I am after.
The link in the incidents link file is simply, source field name, dept.name, target file name contacts and target field name dept.name.
I'm not sure, if I understood your problem. Do you want to fill the deptartment of the contact or do you want to enter a department (or part of it) and select a contact from contacts with this department... Maybe you want to select a department from dept table, then you should use target file "dept" instead of "contacts"..
Ok, basically in the contacts table, there is a text field called dept.name
Which is why I have directed the source to point to the contacts table.
What I would like to do initially is, when I click on the fill button, I would like a list of departments to come up to choose from, then when I click on a department, it selects the department and shows the field on the page.
you have a com/fill field there, right? Fill and combo box are independent. You need a "dynamic select" or a global list (globallists table) for this combo box. Regarding dynamic select check the format "dep.g" and check how it is done in design mode (this is a format to show "Dynamic View Dependency" functionality.
On the link line detail page where link expressions, etc. can be entered, you need to specify in the table below the inital expressions notebook that you only want the dept.name field to be populated using the department name.
If you do not enter field names into that table, all fields in the target record(here, your interaction) which have matching field names in the source record (here department) will be copied back into the Interaction. This is the default behavior when no field mapping is entered. For this reason, I always specify the fields to be copied.