thumbnails and filters not working

Issue Summary

I added an og_galleries view. In the view, I added an Image field (option: Thumbnail) and a filter (only allow Images to the group galleries). But they did not work. I could not see thumbnails when I clicked the group gallery (only showing titles in text) and the content types I did not want to show were still shown in the group gallery. Any idea what the problem is? Your help is greatly appreciated.