Hi Francisco,
You don't need a local variable Date.
You click on the expression where you have the date you want to change, and then double click where it says Value (my example below):

This will open the expression with a value:

And then you change to this:

In my case, it is UserTable.List.User.Creation_Date, you replace by what is in your expression already.
Hope it helps.
Cheers,
João