Cannot communicate with the scanner - unable to Select Source for the scanner
To communicate with the scanners the applications use Twain api
TWAIN is an applications programming interface (API) and communications protocol that regulates communication between software and digital imaging devices, such as image scanners and digital cameras.
The communication with the scanners using Twain works fine with 32 bits but not with 64 bits applications.
For SignLab to communicate directly with these scanners install it as a 32 bits application
If SignLab is running as a 64 bits application then use the stand-alone software supplied with the scanner to acquire the image then save the acquired image in a popular bitmap format (example BMP). Import the bitmap into Signlab using the File - Import menu function.