In Germany, the words false / true (falsch / wahr), based from checkboxes,
are written in lower case letters, and Excel doesn't 'read' it as a boolean.

When I doubleclick on the cells "Falsch" and "Wahr" and then press enter,
the word changes the notation to capital letters. (e.g. "FALSCH"). After this
the calculation works ok.

I think that is a problem with the German and English settings.

Anyone have any ideas please?

thanks