Make sure you select the correct scanner when starting to scan.
For Windows: When you start Epson Scan using the Start button or the EPSON Scan icon, and the Select Scanner list is displayed, make sure you select the model of your scanner.
For Mac OS X: When you start Epson Scan from the Epson Software folder in the Applications folder and the Select Scanner list is displayed, make sure you select your scanner model.
If you are using any TWAIN-compliant program, such as ArcSoft MediaImpression, make sure that the correct scanner is selected as the Scanner or Source setting.
If you are using any TWAIN-compliant application, the error may be occurring because the TWAIN-compliant application is currently unstable. Try using a different TWAIN-compliant application. If the problem persists, try restarting the computer.
For Windows only: Make sure your scanner's name appears under Imaging devices without a (?) or an exclamation (!) mark in the Device Manager window. If the scanner's name appears with one of these marks or as an Unknown device, uninstall Epson Scan as described in Uninstalling Your Scanning Software, then reinstall it as described on the Start Here sheet.