How to change the value of certain column by using IF() expression and touchable button?

i’ve got a problem when using IF expression. Here is my simple app :

So, i have a condition, if my age is greater than 0 than my age will increase +1 and if not, the age will stay the same. but it seems fine untill i click the icon, my age will change into 0 like this :

And these are the way i make the logic :

And i tried to look the test result and it should work :

It return 0 instead of 24, anyone know why???

I’m using google sheet as a dummy db and i’m totally new with Appsheet.