When you see the #VALUE error, it means that there is something wrong with the way the formula is typed, or there is something wrong with the cells you are referencing.

Changing the number format from Date to Fraction doesn't work if the cell already contains a date. You must make the formatting changes before you add the values.

Microsoft Excel normally does not let users change the values of protected cells. To edit a protected cell, you must first remove its protected status.