"You Can't Assign Value to this Object" error on subform

[MAINOH]

I get same error message as thread702-1161841 when I try to enter a new record in a sub-form.

main form data source is tblSDCFSUMMARY with Key field of INVNUM.

Sub-form data source is tblSDCFDETAIL with key field of ID.


There is a 1 to many relationship between tblsSDCFSUMMARY and tblSDCFDETAIL, based on the INVNUM.

Enforce Referential Integrity and cascade Update related fields are checked in the relationships.

I beleive the issue is that when I try to create a new record in the subform - the INVNUM field is not populated in the new record.

Any help in how to automatically populate this field in the source table for the sub-field based on the field in the main form is greatly appreciated. I would want it to populate as soon as a new record is begun in sub-form (no matter what field is 1st to have data entered into it).

Or if you believe there is another issue please let me know.

Thanks!