Using dates in excel

Hi All,

I am using an excel spreadsheet to assit me in acting as a count down

I have recorded the "actual date" and used F4 to lock it.

However I keep getting the days till xx listing a minus number.

For examples:

Today date is stored in Cell A2 (using -TODAY() )
Then I have my column one which is know as START DATE (Coulmn E)

Then I have my column days till tenancy start date (Column F):

I hav entered the formula as:
=($A$2-[@[Tenancy start date ]])

Todays date : 09/09/2018
Tenancy start date: 11/09/2018
Answer shows as: -2

I know there a way to change this
Sadly when i do the formula start date - todats date i recieve an eorro message.

Am i doing something wrong?

Been asked of me tp do this by Tuesday :)

THANK YOU
Jade