The following procedure works fine on my laptop without any problems.
Click on the "Capture" tab and in the options panel select "Screen Capture" . - use that control panel to select the area of the screen you want captured but do not press the 'Start Recording' button.
In VideoStudio now select 'Capture Video' and select your webcam as the input - when you can see your webcam image in the VS preview screen click on the flashing 'Capture Video' in VideoStudio and then on the 'Start recording' button in the Screen Capture control panel.
do what you need to do.
at the end click on "Stop Capture" in VideoStudio and "end Recording" in the screen capture control - after a few seconds two thumbnails will appear in the library - one being the webcam capture and the other your screen capture.