My mainform is based on a table and serves to update the table fields. The subform is based on a query that has calculated fields in it. The subform serves to provide read only information and is set as enable - 'no', locked - 'yes'

The master link field is configured as a combo control (to prevent data modification) and is sorted ascending with an undisplayed primary key autonumber field. The child link field is a text control.

Problem I have is when I tab (the first tab is the master link field) through the mainform, one record to the next, the subform synchronises with mainform, displaying related records. However when I select random fields from the combo dropdown and tab on, the subform remains frozen, and when tabbing into the next record, th subform vanishes. I also note that the master link field in the underlying table is modified to some other value.

Any ideas why this is happening? Thanks.