MySQL error in file: /engine/modules/show.full.php at line 1253

Error Number: 1191

The Error returned was:
Can't find FULLTEXT index matching the column list

SQL query:

SELECT id, date, short_story, xfields, title, category, alt_name, MATCH (title) AGAINST ('Merceds Benz E320 wagon 1994') as score FROM dle_post WHERE MATCH (title) AGAINST ('Merceds Benz E320 wagon 1994') AND id != 398216 AND approve=1 ORDER BY score DESC LIMIT 5