I am working for an organization that manages a magento site for a client. It is running an older (1.6) version of magento, and is unable to update due to compataiblity issues with some of it's plugins and other stuff. I am having an issue. I was asked to replace the PDF invoice logo (The one that appears at the top of the downloadable PDF), and I have tried doing it two ways (One by manually overiding the original file in the /products/media/sales/store/logo, and also by going to System>Configuration>Sales>Invoice and Packing Slip Design, and uploading the new logo there. The problem is, even after flushing the cache, whenever I make a new PDF invoice, or make a new order and invoice it, the old logo is still being used.