Warning and CCK field hidden on node view page for a CCK datetime field formatted with date_picker_formatter

warning: Invalid argument supplied for foreach() in /var/alternc/html/s/spc/lib/php/cms/drupal/6.x/sites/all/modules/date_picker_formatter/date_picker_formatter.module on line 87.

• This warning message shows on node view page.
• The CCK datetime field on which Formatter Selector is applied is completly hidden due to a bug.
• The CCK datetime field is configured with allowed formatters : defauld and date_picker_formatter
• admin/content/node-type/.../display is configured to default

83 function date_picker_formatter_get_votes($node, $field) {
84  $criteria = _date_picker_formatter_get_vote_criteria($node);
85  $date_picker_formatter = array();
86  
87  foreach ($node->{$field['field_name']} as $item) { // warning: Invalid argument supplied for foreach()
88    $criteria['tag'] = _date_picker_formatter_vote_tag($item);
89    $votes = votingapi_select_votes($criteria);
90    foreach ($votes as $vote) {
91      $date_picker_formatter[$vote['uid']][$vote['tag']] = $vote;
92    }
93  }
94  return $date_picker_formatter;
95 }