Assume that you try to search messages in the Search Chat Room History dialog box by selecting dates in the From field and To field in Microsoft Skype for Business 2015 (Lync 2013). After you start the search, you may find that incorrect results are returned.
This issue occurs when you are in regions other than US where the date format differs from mm/dd/yy.
To fix this issue, install the April 3, 2018, update (KB4018334) for Skype for Business 2015 (Lync 2013).
Note Lync 2013 was upgraded to Skype for Business in April 2015.