What settings are you using? If "none" is set as the option then change it to "DV/HDV Device Control". The settings under options should be fine and if they don't work then try changing Device Brand to "Panasonic" and leave Device Type as "Standard" as there is no option for DVX100a. The last option I can think of that you may change in that list is Timecode Format which you can change to "Auto Detect".