Form navigator button not working in LO base

I have been successfully designing forms with subforms in LO Base using the
form navigator. Strangely the form navigator has just stopped working. When
I click on the icon, nothing happens. No further information is displayed.

I have rebooted, uninstalled LO and reinstalled version 4.4.3.2, created a
new test database from scratch and the form navigation button still fails
to do anything. All the other icons in the form design toolbar work.

Help!!!!!

Thanks,

Paul Fearnley

What operating system are you using? My navigator button works. (Ubuntu 15.04, LibreOffice 4.3.3.1.) Base has not had any changes made in it between 4.4.3.1 and 4.4.3.2.

Dan