OK, so it looks like the image is good, and it is located in the correct folder. It is interesting that specifying the <datastore> in the <img> tag shows the image, but the image doesn't show on the Seating Chart page, since the code to display the table essentially does the same thing: it changes "images/greenracetrack.gif" into a path into your data store. So if your data store is in "C:\Users\MyComputer\Documents\The Tournament Director 2\Data", the table blueprint code should transform "images/greenracetrack.gif" into "C:\Users\MyComputer\Documents\The Tournament Director 2\Data\images\greenracetrack.gif".
Can you post your system info? In the TD, press Ctrl+Alt+Shift+V to open the System Info dialog. Press the "Copy to Clipboard" button and then paste it into a reply.