Problem to set the standard value in a combobox in a form

[HiTechCoach]

Note: The default value must be a valid for the bound coulmn (should be the primary key). If the bound column is hidden (column witdth = 0), you still must set the default based on the bound column. Not what is displayed to the user.

In your example, the bound column should be Tijdvak_Id. This a is an auto number. The default value must be a integer. An autonumber will never equal ="wk"&(Format(Date();"ww")).