sprintf(): Too few arguments in catchbase-core

Hey Sakin, I get in my log files the following error message: [Wed August 05 21: 06: 52.687648 2015] [: error] PHP Warning: sprintf (): Too few arguments in / var / www / vhosts / ---- / httpdocs / wp-content / themes / catch-base / inc / catch base-core.php on line 761 Affected line contains: sprintf (_x ('<span class = "screen reader text"> Posted on </ span>', 'Used before publish date.', 'catch-base')), Can you tell me what am I doing wrong? Thank you for your support !