John Witherspoon once replied to one of my questions:
I don't think that will work if you have no or more than one Region selected. I think this will, though (untested):
Basically it means to concat all selected values and compare with that. I don't know if this will work with >=.
the syntax $(=DateFrom) would only return value if a single value is available. For multiple values, you should use min(DateFrom). However, the function min() returns a number and not a date. Set Analysis is very sensitive to the Date/time format. The format of your date field has to be PRECISELY the same as the date format of the other date field. So, to make it work, you need to use something like this:
assuming that this is the date format that you use for your other date field.