I have a custom field :
"Latest Plan Live." (date field)
I am implementing automation to fill in my "Days to fill" field with the number of days.
For example:
Latest Plan Live = March 1
Current Date (calendar date) = March 30
Days to fill should show 30 (?)
I have this formula, but got an error message:

How do I need to update this formula to produce the correct count of calendar days?