Thumbs in teasers generated by nodeteaser module

I have image module and image_attache module enabled.
Before using nodeteaser the default teaser appeared on the listing pages with the thumb from the node attached image.
With nodeteaser enabled, if I let the teaser/sumary field empty.. they are still appear.
However once I start using the teaser the image thumb dissapear from the teaser.
Any ideas how I could add it back?

Thanks