Error message

I’ve just set up Piwik and I’m getting the message below where the Last Visits Graph should be, and “No data” under all the other report headings. I initially used the Wordpress plugin to place the code, then tried placing it manually (in the footer template) but no change in this message. Can you help. Thanks!

JSON Parse Error [Syntax Error]
Error at character 0, line 1:

0: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') AND name IN ( ‘max_actions’, ‘nb_uniq_visitors’, ‘nb_visits’, ‘nb_ac’ at line 3