php error happened

Technical information
Error type8
Error descriptionArray to string conversion
URLconventionhouse.com.au/ACMHN_Accepted/Posters_accepted/Abstracts_list.php?orderby=dAbstract
Error file/usr/home/conv23/www/htdocs/ACMHN_Accepted/Posters_accepted/classes/runnerpage.php
Error line1823
SQL querySELECT Title, FirstName, SpeakerSurname, Job_Title1, Organisation, Address1, SuburbCity, `State`, Postcode, Country, PhoneB, Mobile, Email, Title2, FirstName2, FamilyName2, Job_Title2, Organisation2, EMail2, Title3, FirstName3, FamilyName3, Job_Title3, Organisation3, EMail3, Title4, AbstractTitle, Abstract, Biography, Themes, ID, Accepted FROM Abstracts where (Accepted =1) ORDER BY 28 DESC limit 0,20

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