When ever add photo is clicked, it goes to a blank page. Only when photo icon in menu is selected to view photos is one able to add new photo. So, whats the problem?
Enable debug mode and repeat your action: "When ever add photo is clicked" you should see the actual error. If not, you need to check your server error logs, there should be the error related to the time when you reproduce your action. Paste the actual error here.
IMPORTANT: what is your software version? what is your photo plugin version? do you use oxwall software?