It's possible that you're giving your computer the wrong instructions. The most common reasons why a computer might not be able to carry out your instructions are because they're too simple or too complicated. If you don't follow exact specifications, your computer may not be able to interpret the command you're giving it or it might not have the software necessary to carry out the task. In addition, depending on the type of computer you're using, it might not be physically capable of performing the task. For instance, some computers don't have built-in graphics chips that are capable of rendering complex images, so you'll need to purchase additional software in order to make use of that feature.