Showing error: Failed Security Check: nothing was sent

That is caused because the plugin can’t verify the nonce
For more info on nonce sand why they are important see: http://codex.wordpress.org/Function_Reference/wp_nonce_field

Did you attempt to troubleshoot the plugin ? If not please follow the steps described below:
http://wordpress.org/support/topic/please-read-and-follow-the-following-guidelines-before-opening-a-new-topic?replies=6