Please ensure that the file that you are loading is a tab-separated text file, and that the headings are exactly like those in the sample file. The upload will test for an exact match.
You should be aware that, on uploading, if there are emails due to be sent, they will be sent immediately.
You should also know that you can customize both the email message, and the headings on the feedback form, if you want. This will be important if you are not selling products in the usual sense (e.g. you are a hotelier).