Well.. that is easy... your dates are DD/MM/YYYY bust your regexp is MM/DD/YYYY first section matches 00 to 19, second matches 00 to 39, so many values you pass would fail... 
/^(?:[0-3]\d\/[01]\d\/(?:19|20)\d\d)?$/

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will do it, but as other people have said, there are better ways.

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In reply to Re^3: Quick Regex Question by suaveant
in thread Quick Regex Question by Trihedralguy

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