@HAUSrucker:
decimal marker issue for ('space'.'area') calculation
I had exactly the same issue. Then I realized that the regional settings on my computer are set to Germany (if you are using Windows this is in the control panel>regional and language options). The issue seems to be that in UK and USA numbers are stored as in the format 123,456,789.00, whereas Germany and some other countries are using the format 123.456.789,00. This means the decimal marker in UK/USA is .(point) whereas in other countries it is a ,(comma). The regional setting seems to have an effect on the calculations of the Vectorworks worksheets, as if Vectorworks doesn't recognize anything behind a comma. After changing my regional setting to UK every newly created space in Vectorworks came up with a .(point) and best of all the =('Space'.'Area') works and also simple =sum() calculations are working again.
I am not sure whether this will solve your problem, but given your user name it sounds as if you are based in a German speaking country and it might well be the same issue.