Image replacement in Showcase Flash Slider

I’m not having much luck changing the images in this slider. I have created 3 new images for slides 1, 3 and 6 – made them jpegs, 900×400 px – file size is about the same. I moved and renamed the original image1, 3 and 6 into a separate folder in Showcase/images. The end result is – no change. Any suggestions?