Provided by Allen Browne, January 2008. Updated: April 2010
Calculated expressions show #Error when a form or report has no records. This sort-of makes sense: if the controls don't exist, you cannot sum them.
The problem does not arise in forms that display the new record. It does occur if the form's Allow Additions property is Yes, or if the form is bound to a non-updatable query.
To avoid the problem, test the RecordCount of the form's Recordset. In older versions of Access, that meant changing:
=IIf([Form].[Recordset].[RecordCount] > 0, Sum([Amount]), 0)
Access 2007 and later have a bug, so that expression fails. You need a function.
Copy this function into a standard module, and save the module with a name such as Module1:
Public Function FormHasData(frm As Form) As Boolean 'Purpose: Return True if the form has any records (other than new one). ' Return False for unbound forms, and forms with no records. 'Note: Avoids the bug in Access 2007 where text boxes cannot use: ' [Forms].[Form1].[Recordset].[RecordCount] On Error Resume Next 'To handle unbound forms. FormHasData = (frm.Recordset.RecordCount <> 0&) End Function
Now use this expression in the Control Source of the text box:
=IIf(FormHasData([Form]), Sum([Amount]), 0)
Use the HasData property property, specifically for this purpose.
So, instead of:
=IIf([Report].[HasData], Sum([Amount]), 0)
If you have many calculated controls, you need to do this on each one. When Access discovers one calculated control that it cannot resolve, it gives up on calculating the others. Therefore one bad expression can cause other calculated controls to display #Error, even if those controls are bound to valid expressions.
For details of how to do this with subreports, see Bring the total from a subreport onto a main report.
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