Newly watermarked images not loading when viewing site

I started adding watermarks to my images to help protect the items that I craft by hand. I tested out the new images, made sure they were proper size - dimension as well as file size, and uploaded them to the /images/ directory.
However, when I view the items with the changed images, I do not see the watermark.
When adding the watermark, I did not change the file name, it is exactly the same as the original image, and I made sure that the Filezilla was set to overwrite the file on the server.
I have viewed the changed products in Chrome, Safari, and IE, and I am unable to view the changed items.
(I did clear the cache, and ran CCleaner to make sure I was fresh when viewing the site.
This is a frustrating ting, and I am sure I am missing something simple.
If anyone out there has some pity, and would like to proffer some help, I would be very grateful.
Thanks,
Kirby

If you right-click on the image and choose Open Image In New Tab, what happens?
Does it show you the new image?
Does the URL it takes you to match the path of the file you uploaded as a replacement?

Do you have some sort of image managing plugin added to your site, which has cached all your images to different paths outside what ZC was built to do? If so, you'll probably need to reset that cache.