When i receive an email notification for my form, it just says undefined. There is no form attached to the email. What am I doing wrong?

My form Trader registration has just been added to my website. The first time someone has tried to use it I have recieved an email saying UNDEFINED. Not sure what I have done wrong or how to amend this.

I checked your form and the body of the email does not look to be empty.  The empty notification may have been a temporary issue.  I cleared your forms cache to ensure there was not a caching problem.  Try submitting the form again to see if the notification triggers properly.  If it comes through as "undefined" again, let us know and we will be happy to have another look.