MySQL error in file: /engine/modules/show.full.php at line 901

Error Number: 1191

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

SQL query:

select id,title,alt_name FROM news24h_enusa1crosvrd where MATCH(news24h_enusa1crosvrd.alt_name) AGAINST('affected adult line\'s mobile ringtone sender?') limit 18