Problems setting meta tags configuration up

When I try to set up the configuration in the default values first, I get this error:
warning: mysqli_real_escape_string() expects parameter 2 to be string, array given in xxxxxxxxxxxxxxxxxxxxx\includes\database.mysqli.inc on line 323

But the information is saved, but the robot option that I don't need FOLLOW is not saved as I checked.
So, if I try to update configuration again without this option then I get these errors:

* warning: array_filter() [function.array-filter]: The first argument should be an array in xxxxxxxxxxxxxxxxx\sites\all\modules\nodewords\nodewords.metatags.inc on line 603.
* warning: array_keys() [function.array-keys]: The first argument should be an array in xxxxxxxxxxxxxxxxx\sites\all\modules\nodewords\nodewords.metatags.inc on line 603.
* warning: in_array() [function.in-array]: Wrong datatype for second argument in xxxxxxxxxxxxxxxxx\sites\all\modules\nodewords\nodewords.metatags.inc on line 605.
* warning: mysqli_real_escape_string() expects parameter 2 to be string, array given in xxxxxxxxxxxxxxxxx\drupal6\includes\database.mysqli.inc on line 323.
* user warning: Duplicate entry 'default--robots' for key 1 query: _nodewords_set /* admin : _nodewords_set */ INSERT INTO nodewords (type, id, name, content) VALUES ('default', '', 'robots', '') in xxxxxxxxxxxxxxxxx\drupal6\sites\all\modules\nodewords\nodewords.module on line 964.