Please ensure that you have the correct version installed on your computer before attempting to purchase it. If you have the wrong version then you can download it from this website.
The registration key only works with the latest version of S_Merge.
Do not download S_Merge from unauthorised sites as it can come with extra baggage such as a virus. If you are in any doubt then download it from this website.
Most problems can be answered by looking at the FAQs page here. It will be updated regularly and is more up to date than the help faqs within the program.
If all else fails then email Graphicutils with your problem. I will get back to you within 48 hours.