Image Gallery

I have the latest version of the Image Gallery installed. I have added some additional fields so it is customized for my website needs. I have not messed with anything dealing with the images. But when I go to update a picture on an already existing entry by clicking the add image button it brings me to a new image entry not to just add an image to the already existing one. Also If I click the delete image checkbox next to the image and click save, it deletes the main image and not the original or thumbnail images. So, when I pull up the gallery the thumbnail is the old picture while when you click on the thumbnail the larger image is the new one I just uploaded. I temporarily fixed my problem by going in the image folder and deleting the thumbnail before uploading the new image and then it works. But is there something that would cause it to not delete all three of the images?