How to navigate between sheets

Sir I have recently installed the following version of Libreoffice ,
Version: 4.3.5.2
Build ID: 3a87456aaa6a95c63eea1c1b3201acedf0751bd5
but in CALC , when I am trying to navigate between sheets , the Ctrl+Pagedown command is not working . I have tried customising, resetting , but it simply refuses to happen . Conversely , Ctrl+Pageup is working …Please advise

I am also using 4.3.5.2 on an XP machine and it works for me fine.

May I propose to file a bug report here: https://www.libreoffice.org/get-help/bug/