@Benhill hello there. Could you be more specific about what doesn't work exactly? Since dates are essentially numbers (i.e. serial numbers), a comparator can be used without issue. The formula provided above ensures both dates entered are actually numbers and not text, which could very well be your problem. An easy way to check is to remove any horizontal alignment and widen the column; if the data is left-aligned it's seen as text, whereas if it's right-aligned it's seen as numerical (including dates). If this is the case, either coerce the textual date to be numerical, or coerce your formula dependencies. Generally it's better to do the former.