MySQL error in file: /engine/modules/show.full.php at line 1024

Error Number: 3685

The Error returned was:
Illegal argument to a regular expression.

SQL query:

SELECT id, date, short_story, xfields, title, category, alt_name FROM dle_post WHERE category regexp '[[:<:]](23|27|26|24|26)[[:>:]]' AND MATCH (title, short_story, full_story, xfields) AGAINST ('LG тоже планирует выпустить «умные» часы и очки По материалам: www.iguides.ru') AND id != 935 AND approve=1 LIMIT 6