How to subtract days from a date

I have a column called 'job requisition freeze date' and a column called 'total number of days frozen'. The 'job requisition freeze date' is formatted as a date. The 'total number of days frozen' is formatted as a whole number.

I am trying to take away the 'total number of days frozen' from the 'job requisition freeze date'. In my example:-

'job requisition freeze date' = 30/09/2021

'total number of days frozen' = 36

so the answer should be = 25/08/2021

Below is the formula I am using:-

DATEADD('day',-[Total Number of Days Frozen],[Job Requisition Unfreeze Date])

However, for some reason the answer is coming out as 29/09/2021?

Anybody any ideas how I can resolve this?