Pinboard theme doesn't use thumbnails on frontpage?

Hello,

I’m working with the Pinboard theme now. For some reason it seems that it doesn’t use the generated thumbnails on the front page, but it displays the full size images shrunken down. It slows down the page a lot and doesn’t really look good, but I cannot make it use the thumbnails like it should. Does anybody know why this is happening?

thx
greg