update your epson drivers.
You need to install the TWAIN plug-in from Adobe Exchange.
Moving this discussion to the Photoshop General Discussion.
Sharon I believe both KGlad's and Mylenium's suggestions are valid. Users in this discussion forum may have additional solutions to offer if the first two suggestions do not resolve the current difficulties which you are experiencing.
Are you on Mac or Windows? The scanning solutions are different on the two platforms, so that is important to know.