How are you adding your images from Picasa? Are you adding them through Picasa uploader that is built into the app or are you pasting the url to the photo into the app?
First make sure your photo is shared publicly through in Picasa. We cannot display private images. Also, if you are pasting the URL to the photo, make you you copy the photo's url and not a webpage with the photo in it. The url should have a ".jpg" ending. Many photo hosting sights, like picasa, will display the image within the a webpage when you click to expand it. Instead of copying the url in the browser's url bar, right click on the photo and choose "Copy photo link" or "Copy photo url."
If you still have issues, let us know.