@LeeHarvey there is missing Var at the beginning so:
Var
ClickVol : Widget
On WidgetValueChanged (newValue : double) from ClickVol SetMetronomeVolume (newValue)
end
edit: script is in this post https://community.gigperformer.com/t/feature-requests-from-new-user/537/9?u=keyman with an example gig file @Wired 