Activation Code Problem

Hello by activation required enetering purchased Code it shows folowwed Error: <div id="message" class="updated"> <p class="cr_failed_notif"> Plugin registration failed! </div> <div class="notice notice-error is-dismissible"> Automatic updates for this plugin are disabled. Please activate the plugin from below, so you can benefit of automatic updates for it! From Log, Activity and Logging: Invalid json from purchase code verification: <h1>Not Acceptable!</h1> An appropriate representation of the requested resource could not be found on this server. This error was generated by Mod_Security. Please Help </div>