You've told us nothing about how you've installed your software, how you've set it up, and how you're trying to get it to work.
That said, if you are trying to run it via TWAIN, note that the TWAIN plug-in is an optional installation with CS4 and needs to be installed manually.
And that said, note that the reason why it is now an optional installation, is that a number of scanner manufacturers are not complying properly with TWAIN standards.
So, I recommend that you use the standalone software that Epson supplies, and scan independently of Photoshop. A great benefit in scanning this way is that you are not tying up Photoshop as a scanner utility, and you can work productively while scanning.
Hope this helps.
Neil
I must agree with Neil. Tying up a $1000 application as a scanning interface is a bit silly since Photoshop has no scanning ability in and of itself. You are still using Epson's software. So since this a new scanner and a new version of Photoshop try doing a new way.
PS is a terrible workflow hog
The exception would be (first assuming that TWAIN-compliant software has been provided by the scanner manufacturer) if you are doing only very occasional scanning.
Neil
the girl that works with me is a person of habits and might want to import
the scanner the old fashion way
Just make it clear to her that she does it at her own risk, and crashes and other problems are quite likely.