Imagecache and articles

I was wondering about the way that images are associated with article.

When I use the main image/thumbnail image the files are uploaded to sites/all/files (which is the default path) with the thumbs going to a folder called imagefield_thumbs that is created on the fly. However, the template is trying to pull the images for the article from the imagecache folder so it displays a broken image.

The same goes for the Author image assigned in the author content type.

When I look at the author image and click the crop option and select a preset then Imagecahce seems to behave properly. But I'm having no luck when it comes to an article image.

I'm right in thinking (I think) that the imagecache module creates sub-folders in an imagecache folder based on image cache presets. So it seems that something is not connecting here. Am I doing something wrong?

Is it a template call that is wrong? Do I need to set-up a new imagecache preset and, if so, how does that map to the fields in the article page.

I'm aware that I might be missing something really simple here, so apologies if I'm being dim. But any help would be great

Best

Andy