You don't need a field for this. FileMaker has a shorthand notation for the session date which refreshes every time the window changes, so it's always the current date unless the user walks away from it overnight and it is still open unrefreshed -- hard to even make that happen.
Create a text block and use the Insert menu in layout mode: Insert > Date Symbol
Don't use the Current Date from the insert menu or it will insert the actual date as text, rather than the symbol that updates as the day changes.
You can select the text block of this inserted merge-symbol and format the date using the inspector so your date has the look you want on the layout.
Thanks for that info. I'd still like to know why my calculated field displays 0/0/0??
You may have hand-typed the calculation rather than pulling it from the list of functions, and there could be a minor typo.
When I enter it from the function list it is: Get ( CurrentDate )
It is also pulling data from the record of it's own table, and from the OS system date (which could be wrong), might be in an unrelated table so returns no value, and, even stranger is that sometimes the related table has no actual record. While some global fields work fine even from tables with no records created, other seem to require an actual record (or related record) to return a value other than null.
use an unstored non-global calculation - if your window doesn't get refreshed or redrawn after midnight it might display the wrong date ..
Also be mindful of the date format of the field. If you accidentally set it to "Custom", there may be some weirdness going on there.