A family of Microsoft relational database management systems designed for ease of use.
Unfortunately, we don't have visibility to the actual table or the linked Excel file, and especially to that expression which is failing.
Put the situation into context for us. Show us the table, make sure to clearly indicate the table-level validation expression which is failing. Also, it would be VERY helpful to have an explanation of the context, i.e. what is the goal and purpose of the validation?