Use of calculated Values in a Form

[walterwerner]

I have a query. The data to be displayed is properly available in the query.
I use a subform. The subform is correctly pointing to the query.
When accessing a field in the query, that is basically a copy from another field, the data is displayed correctly.
When accessing a field in the same query that is calculated in the query there is no data displayed.
→ Same happens when I do the calculations directly in the subform (using SQL)
→ It works fine if my subform only uses a “sum” field (of the query or direct SQL): That calculate data is displayed correctly.
→ When the data is a calculation that uses multiplication and summation it does not work (But: The query shows the correct values…)
Calculations are not really tricky:

Select "Kunden"."Produkt1Kosten"*"Rechnungen"."Produkt1Anzahl"+"Kunden"."Produk2Kosten"*"Rechnungen"."Produkt2Anzahl"+"Kunden"."Produkt3Kosten"*"Rechnungen"."Produkt3Anzahl" AS "Summe"
FROM "Kunden", "Rechnungen" WHERE "Rechnungen"."Kunde" = "Kunden"."ID"

→ All fields are correctly referenced.
I am really stuck here, sorry.

[Villeroy]

https://forum.openoffice.org/en/forum/download/file.php?id=37976

[walterwerner]

Finally found: The WHERE clause was not sufficiently small formulated, with “copied” results in the query the data in the field was always identical, but with calculated results the values were ambiguous and therefore not displayed.

[Villeroy]

IMHO, there should not be any WHERE clause.
Main form shows clients. Subform shows invoices related to the selected client.
Subform data properties:
Link master fields: ID
Link slave fields: Kunde (if “Kunde” has the foreign key referencing the ID of table “Kunden”)