>In the imageurl I copied the name of the image as it is placed on the root. So it is not relative but full. The strange thing is that if I hide this form under the login form, then when I give the user name and password to display the same page, I can see the image.

I'm assuming it's showing the little red X. View the source of your page in the web browser to see where it things it should be. I had this problem before and I remember that's how I figured it out. Unfortunately I don't remember what I did.