I think your device is undetected
Have you followed this instructions:
Driver Installation Instructions:
1. Put your Samsung Galaxy S into download mode and plug it in.
2. Run zadig.exe included in the Drivers subdirectory.
3. From the menu chose Options -> List All Devices.
4. From the USB Device list chose "Samsung USB Composite Device".
5. Press "Install Driver", click "Yes" to the prompt and if you receive
a message about being unable to verify the publisher of the driver
click "Install this driver software anyway".