Xperia Z2 (Kikat 4.4.4) - STAMINA mode does not work? STAMINA mode does not work on my Xperia Z2 - Kikat 4.4.4 (latest version)

I found a discussion in this 
https://talk.sonymobile.com/t5/Xperia-Z2/Xperia-Z2-Stamina-mode-doesn-t-work-aparently/td-p/793097?sl=y&amp;sso_no_log=y

but I can not find "Eco mode controller" in Apps list.

Anyone has any ideas? Thanks!
I think they renamed the Eco mode controller app with the 4.4.4 update to Stamina mode...  So scroll down until you find that app. Take note of the estimated days and hours before you force stop, clear cache and restart your device. 
activate stamina mode again after boot and note the change in estimated days and hours. 
Hope this helps!