Webform Report Error

I just installed Webform Report module and created my first report.

Drupal 7

However, I received the following error when I tried to Preview the report.

"Unable to display webform report - possibly damaged node."

"Notice: Undefined index: sort in __lambda_func() (line 1 of /home/mighty/public_html/drup/sites/all/modules/webform_report/webform_report.inc(1112) : runtime-created function).
Warning: usort() [function.usort]: Array was modified by the user comparison function in _webform_report_sort() (line 1112 of /home/mighty/public_html/drup/sites/all/modules/webform_report/webform_report.inc)."