Changing map size generates map error

Everything was working great when I added the widget to the website footer, but changing the map size generated an error. When changing the thumbnail size from 250px to 339px, the map was replaced with a grey background and an error saying “This site can’t load google maps correctly.” Changing the size back to 250px makes the error go away, but I need a bigger size. thoughts or suggestions?

The page I need help with: [log in to see the link]