fcp 3 to fcp 4hd capture

hi !
I´d recently upgrade from system 9 to osX and of course from fcp 3 to fcp 4.
Now It´s impossible to capture to an external hd in fcp 4 osx.
when capturing the image stills or get like time lapse capture.
when I switch to system 9 in fcp I can capture pretty well.
Whats wrong???