Could not insert invitation record

I’m having some trouble with the “Create Training” step.

I’ve created a page and embedded my course. When I Create Training, I select the course, select All Users (tried the other two options as well with no success) and click Create Training, It is presenting the following error:

Could not insert invitation record.

Any help would be appreciated.

http://ww.wp.xz.cn/extend/plugins/scormcloud/