Logic 10.1.1 exporting audio to movie...

There are two boring troubles:

1. Sometimes after exporting audio to a piece of movie (using locators) I hear my sounds but I see only a white screen!!!!

2. Sometimes after trying to make a short piece from the whole movie (using locators) I got the whole movie in (instead of a short piece) and my sounds start from time-code 00:00:00...

What am I supposed to do with those???

Thank you!