I think what you have and what you want are two different things.

What you want (from your post, I hope I am not misreading it): is to check if the date string is the way you want or is empty. What you conditional states is: if the date string is not the way I want OR $_ is NOT EQUAL to '' then set the $Flag variable

What I think you want is: if the date string is not the way I want AND then $_ is not equal to '', then set the flag.

if (! /\d{4}\-\d{2}/-/d{2}/ and $_ ne '')
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or

unless ( /\d{4}\-\d{2}/-/d{2}/ or $_ eq '')

Update: As posted below, you will want to look at the regex as well, as I unfortunately did not bother to check to make sure that was working when I was looking at your code (and hence made no modifications to it). Thanks tachyon

-enlil