php error happened

Technical information
Error type256
Error descriptionUnknown column '' in 'order clause'
URLwww.daltondatabank.org/DDBIndex/Limerick/baptisms_list.php?orderby=aLocality
Error file/home/golde89/public_html/daltondatabank/DDBIndex/Limerick/connections/Connection.php
Error line661
SQL querySELECT `Date`, `Child`, `Parents`, `Sponsors` FROM `baptisms` order by `` ASC limit 0,20

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