My form is derived from several tables, some without RI as records being added are often creating new primary fields for the related tables, so I turned off RI, established two SubForms, so that the new entries can add in easily. The related tables are operating basically as Lookups Only whilst I test all functionality of the Form.

However, one table has a linked field creating the Error :
"Cannot enter value into blank field on one side of an outer join"

Is it possible that this is occurring because of the 3 tables set for non RI only this one is operating without a sub-form?