You need to link your main form and subform using the LinkChildFields and LinkMasterFields properties. For information on linking a main form and a subform, click .
If you've already set the LinkChildFields and LinkMasterFields properties and the subform still doesn't work, make sure that you aren't using fields that have been renamed or deleted. Also make sure that you've spelled the field names correctly and that you're using the actual field names, not the control names specified in the Name property.
Note Under certain circumstances, Microsoft Access will automatically link a main form and a subform when you use a wizard to create the subform. For more information, click .