Few check ups you could do before starting your Manual
Recording:
1. Launch Captivate and press Shift + F8. This would launch
preferences dialog. Goto Recording:Keys, see the Manual Recording
section and verify that your desired key is selected to take the
screenshot.
2. At Recording:Keys, go through all the set keys and
options. In Cp4, we have a facility that triggers Automatic Paning,
Manual Panning, Full Motion Recording while recording. So please do
not press those keys while Manual recording is ON.
3. If you do not want the Keystrokes to be generated in your
Manual Recording, then goto Recording:Settings and uncheck the
"Keystrokes" check box.
After performing all the above check ups, please try Manual
Recording. It should work now.
-Manish
http://blogs.adobe.com/captivate