Please clear your browser's cache and try again. You should see a pop up with an error message if the picture you tried to upload does not meet the requirement. If you have the pop up blocked, please add Wishpool to the whitelist.
If there is no error message, please send us a screenshot of the failure page, and tell us the URL, browser and its version, and the operating system you are on. Please email them all to firstname.lastname@example.org, and we will look into it asap.