play movie

1
Hi,

Thanks for all the information helping me with the movie playing. now
i can use the following command to open and play the movie.

moviename='tale.mov';
movie=Screen('OpenMovie',window, moviename);
Screen('PlayMovie',window,movie);

but the next problem is that i really can hear the sound in the
beginning of the movie, but i can't see the image of the movie; also
the movie can only last about 7 seconds rather than the whole time~~

do anyone have any idea about this? should i do something to modify
the image or other items, for example, the rate of the movie?

cheers,
Yue