Discrepincy with e-snips

I was wondering if anyone had any trouble uploading their files to the website. To be fair i have successfully uploaded 3 of 4 files. However i am having trouble with my final one, it has uploaded but is unwilling to play through the website. I wondered if any one else has had a similar problem and been able to solve it? This to me has again highlighted what lecturers have said with the need to back up your files, so i will definatley be doing from now on.