Import images with feeds

Hi,

I am trying to import product entities with Feeds. I use Commerce Feeds in addition to Feeds and my importer works well except for the images...
This keeps giving me problems.. I create a CSV which I import with a Feeds Importer, in my CSV I have all sorts of fields and also an image field (public://products/productX.jpg for example) or the image field could be blank (no image available). But when I add the image field to my importer OR when I leave it out of the mapping it keeps giving errors.
I keep getting Integrity constraint violation: 1062 Duplicate entry '' for key 'uri' for some of the products and no products seem updated...
I'm struggling with it for days now so any suggestions or help would be greatly appreciated!

Thanks in advance!