"Could Not Enable TWAIN Source" or "There Is No Scanner Found" Error Messages Are Displayed

If you cancel an in-progress scan from a third-party program that is obtaining images from a Windows Image Acquisition (WIA)-supported device, you may receive the following error messages: -or- NOTE: This behavior has been reported in third-party programs, such as, Picture Works PhotoEnhancer version 3.2, Adobe Photoshop, and CorelDRAW. Also, this behavior has been reported in Microsoft HomePublishing 2000.

In Windows 2000, this behavior does not occur: Programs do not generate errors when they are cancelled.

This problem can occur because the third-party programs are not properly handling the return value, which must follow the technology without an interesting name (TWAIN) specifications.

To work around this problem, close the dialog box that contains the error message, and then continue with your task.

Or, to resolve this problem, obtain updated drivers from the manufacturer of your third-party programs.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

The TWAIN compatibility layer enables a program to communicate with a WIA device. This layer is represented as a modal TWAIN data source. When the layer is started or enabled, the user intends to either transfer data or to quit the operation.

With a modal data source you have three options for TWAIN return codes:

• Failure: An error occurred that prevents the TWAIN data source from transferring data.
• Success: All settings are complete, and the operation is ready for a data transfer.
• Cancel: The user has closed the user interface and does not intend to transfer data. (The operation is either cancelled or closed.)

The previously listed third-party programs place the return codes into two categories: Pass or fail. The "cancel" return code is grouped with the "failure" code.

The programs that misinterpret the return codes can cause the error messages to be displayed. A user can read the error messages and follow the actions that are stated by the program to attempt to correct the problem, but the attempts by the user to correct a perceived problem are unnecessary.

The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.