Well then you may want to contact the customer support group for the camera(s) you have and tyring to use. If there are no “sources” listed when you display the Select Source dialog then it sounds like the TWAIN driver wasn’t installed.
If there are no sources listed then there isn’t much else you can do. The driver installation will typically place its Data Source in the TWAIN_32 folder in the Windows directory. Are you installing the software and TWAIN driver for the camera when you are logged on as “Administrator” or using a User name that has Administrator privileges?
Brian