The date a value of a sensor changed

Configuration Frontend
1 
This gives me the date of today. But when I look , it didn't change

![afbeelding|690x257](upload://kcFAOgrdeaMZgoSzewdWSFQ42w6.png)

but here it does...

![afbeelding|234x142](upload://s4cuZpKHBVDu6aJxAxESYQbAbmH.png)


What is the right code ? because last changed and last updated give me the same, wrong date...