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Hi, yes the problem is on the jQuery file https://orgchem.by/wp-includes/js/jquery/jquery.js?ver=1.11.3

The error is that a parenthesis is missing, and jQuery doesn’t exists and then my plugin doesn’t work.

Well, and how will I correct the problem?

Try to use another jQuery file, reupload it, or just use the plain one included in WordPress. Don’t change it to a custom one.