Using field names, field values, and expressions in workflow
When you are creating workflow, field references almost always refer to the Primary Form defined in the Associated Forms panel. This includes fields used in Execute On options and Run If actions. Fields to be used by workflow must exist on the Primary Form. Fields found on other associated forms are not displayed as selectable values in the field selection dialog for most workflow actions, or as part of the auto complete feature in qualification or field selector dialogs.
An exception to this is when a workflow action references a second form, such as Set Fields and Push Fields actions, where you can select fields from both the primary form and the secondary form, or an Open Window search action, where you might search for data in another form.