Reject input if the adjacent cell is empty

Question

Using below formula to Reject input if the adjacent cell is empty.

I am trying to made the condition for the Data validation rules that if R2:R500 is empty then Column M will Reject the input when try to add anything but below formula is not working in Validation.

=NOT(ISBLANK(R24))

Here is my Sheet

Answer 1

Try this validation setup.

=$R2:$R500<>""