Does anybody know why I got this strange message when I try to Submit : "unknown error: undefined method `+' for nil:NilClass"?
First, check the way you quoted the positive sign `+' . Did you try to create a filename by using this `+' . May be you should change it to '+' instead `+'. These are the same signs but quoted differently.
Please make sure your whole submission file is filled. If there are blank values rather fill them with 0.
Thank you, guys.
I had some empty fields, actually (wrong submission shape). I've fix it and it is working now.