Could you please show the SQL statement for the query? What SQL Server driver are you using in your connection? Have you tried to add the primary key to the query?
Cheers,
Vlad
Long shot:
Is the field "AbsentHoursID" included in the query? I've had problems adding records to tables if the table PK field is not included in the form record source. I will add a control for the PK field, but make the control hidden on the form. (and I set the bkground to yellow to indicate that the control is hidden)
HTH
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Steve