Error message: Notice: Undefined index: dataviz_load_bigtext in views_dataviz_plugin_display_extender_dataviz_bigtext->pre_execu

First, I like to thank for the great work, I had try a lot of chart modules before, but in vain, until I find this excellent module. This module work with views (without any php code in body field). However, the error message was appear in my site:

Notice: Undefined index: dataviz_load_bigtext in views_dataviz_plugin_display_extender_dataviz_bigtext->pre_execute() (line 15 of /Users/Nana/Sites/sandbox/sites/all/modules/views_dataviz/views_dataviz_plugin_display_extender_dataviz_bigtext.inc).

How can I fix it?