Possibly because you have a popup blocker. Or otherwise your files may be corrupt or incorrectly named, or you using a non standard web browser. read on
If you have a popup blocker. Look for popup blockers in your tool bar.. click them and "allow popups from this website permanently".
If you see an error message like "DEMO ONLY" then you may have been logged out, and you need to close all your browser windows and re login again...
Make sure your photo filenames contain only alphanumeric characters and no spaces and no strange characters excepting full stop, hyphen and underscore. eg .-_
Perhaps the photo is too big and it is just taking a long time to upload.
Or perhaps you have a TIF or BMP or other image format that is not accepted on the web or in our CMS. Note PDF and DOC files are not images, even if they contain images. You should only use JPG, JPEG, GIF or PNG for images.
Or otherwise you are either on a Mac, or using Firefox, and you are trying to edit one of our single design pages, then there is a known bug with the form "focus" of these computers and browsers. Sometimes it works, sometimes not, depending on versions... Sorry about this, but it's hard for our system to work on every browser in existance, each trying to use very advanced dynamic HTML features. Please if you try using Internet Explorer on a PC, you might have more success... We will in due course fix these bugs, but it all takes time.
If the problem is not one of the above, then please consider the following:
Do you get any error messages? If so, please let our support team know what they are.
How far do you actually get - do you see the popup image wizard? Do you see a browse button? Did you browse for your file and return to the wizard? Did you click upload? Did you click "use this image"?... how far you get in this process is very important information. Please let us know how far you get, so we know the likely cause of the issue, but please read on.
If you got past the browse stage, then how big is the file you are uploading? Is it very large? If it is over 100kb or over 1MB, then this is a big file that will take a while to upload. You may need to wait a minute or 2 for it to happen. If the file is over 1 megabyte, then it might just fail completely.
What type of image are you uploading? What is the filename? does it end in .jpg or .png or .gif? if not, is it really a photo.... just because word files and PDFs contain images, it doesn't mean they are images... you will need to abstract the images out of those documents if you want to use them
Does your image filename contain any illegal characters? eg spaces or non alphanumeric characters... images should only have names with letters, numbers, dashes, dots and end with .jpg or .gif or .png
Is the problem you just can't see your image? Perhaps a red box with a cross in it? Is your image viewable when you double click on it on your own computer? If not, it's probably not an image, or it is corrupted. Once you have confirmed the image is viewable on your own computer, then you should have more luck.