Error installing Classipress theme
I have just purchased Classipress and the version available in my account is version 3.1.8. I have just tried to activate the theme by I keep getting this message:
Fatal error: Call to undefined method WP_Query::is_main_query() in /home/discover/public_html/courses4medics.co.uk/wp
-content/themes/classipress/includes/theme-actions.php on line 253
I have tried installing the theme using the word press theme installer (Appearance>>Install themes>>installed the .zip file) and I have tried installing classipress via FTP using FireFTP (the unzipped version).
No matter which way I try, I still get the error message.
I have tried uploading other themes such as the twentyten and have no problems here.
Additional information: I am currently using WordPress 3.1 and I have no plugins installed.
I would be grateful for any help here.