When you acquire images from your TWAIN compatible device, you may receive the following error message returned by the ErrorString property.
The problem may happen when the process does not occur in a particular sequence.
Please check if you followed the acquisition sequence to get images from your device. For example, some methods and properties, like the PixelType property, can only be used after calling the OpenSource method. Please check the TWAIN State Transition Diagram below for more information