DSUM problem, on Ubuntu

Hello,

I have a problem with DSUM. It always returns 0, even with using the example in LO help.
https://help.libreoffice.org/Calc/Database_Functions#Example_Data
https://help.libreoffice.org/Calc/Database_Functions#Example_11

I’m using version Version: 5.0.5.2, on Ubuntu. Build ID: 1:5.0.5~rc2-0ubuntu2, Locale: en-US (en_US.UTF-8).

Thank you.