Why does the movie I capture with my Logitech camera not have sound?

Make sure you are using Logger Pro 3.5 or newer. Earlier versions for Windows were not able to capture audio from Logitech cameras. Updates are available at:
www.vernier./tech/lpupdates.html

When Logger Pro does video capture, it can capture sound from any available sound source on the computer. If, when you first set up the camera, you choose the internal sound card (or other source) then the captured videos will probably not have sound.

To confirm that the sound source is set as you want (which is probably to the Logitech), connect your camera, start Logger Pro, and choose Video Capture from the Insert menu. You should see a video image. Click Set Up Camera to enter some set up options. The first dialog lets you choose a resolution. Choose one. Then, you may get a dialog asking you to choose sound source. Choose the Logitech, if available. The Logitech may show up merely as "USB Audio Device."

Then click OK, and test.