There are four reasons that PROOF may not appear on your photos:

1. The word PROOF only appears to guests. 

Account owners would not want to see PROOF on their photos all the time. To assure yourself that the watermark is appearing, sign out of your dotPhoto account, open a new browser, and look at your account as a guest.  If you are setting up a web site, you can see your site by substituting your login name for "www" like this:

http://<mysignin>.dotphoto.com

If you have a guest password, sign in as a guest here:  https://www.dotphoto.com/signin.asp

2. The original image was too small. Only images greater than 1280 dots on the longest side are watermarked in single-image view.

Watermarks are meant to protect important images for which you own the rights. Images under 1280 dots on the longest side are not protected by watermark, and, in our experience, may be copied from the web. You can remedy this by uploading a larger original image, or up-sizing the image prior to uploading it.

3. The images were not uploaded with the watermark process.

4. The images were uploaded once without the watermark, and uploaded again WITH the watermark.

When dotphoto sees an identical image uploaded a second time -- regardless of the name of the image -- it uses the original image. If the image is changed by only a single pixel, the image is interpreted as a new image, and the watermark is added. Unfortunately, if the same image is uploaded again, the watermark is not added. This can occur even if the image was uploaded once before as part of another album: this will result in some images having watermarks and the images that were previously uploaded without watermarks missing watermarks in the new upload.

We are seeking an improvement to this. The current workarounds are (1) change the size of your images slightly before uploading them again or (2) send the name of the original album to support@dotphoto.com so that we can remove the memory of the original images from the system before you upload again.

More on watermarking