loadMovie starting at certain frames

Hi,
a small problem, as I´m not able to find the right code.
Down the code that works:

on (release) {
loadMovie(“blok.swf”, “_root.screen”);
}

It will open blok.swf from the beginning.
My interest is to have different buttons using this code, but opening the same *.swf, in this case blok.swf, but at a certain frame, not all at the 1st.
This way I don´t have to use tons of different *.swf´s

please help!

thanxxx