The various source sites sometimes change their data structure, and the way older images are archived.
While many of the sites go back for years, I have decided to limit Pic-a-POD to dates on or after 1st January 2009.
To search for older pictures, get the details view for a picture from the relevant source, click the network icon to see the picture in it's original web page, then look for a link to Archives to see older pictures from that site.