applying a mask to layers which follow a motion guide, not working

[impsvi]

ooh arrrr, for some reason when i try to apply a mask to a guide layer and the layers below it (gfx which follow the guide), the layers dont get linked, the mask therefore doesnt work.

I tried placeing the mask layer inbetween the guide layer and the guided gfx layers blelow but it would not let me.

Can you do this in flash? were am i going wrong, my animation is quite simple: small molecule like circles follow a guide layer which is a line.
At a certain point in the line i want the molecules to be visable then further along the line it want them to dissapear. I thought a mask would best achieve this but it doesnt work.

Im using flash8 but publishing in mx2004, i would upload the .fla buts its to big and im not really suspose to make the content public not thats its secret or anything but beacuase its for a museum, i have included a pic tho.

thanks

[raskolnikov]

do it with actionscript instead of guided mask.
make your animation of your mask in one mov clip
name it say "mask1"

on your root make 3 layers.
one for the mask mov you just made "mask1"
one for the masked image, make this a mov clip too, name it "image"
one for actionscript put image.setMask(mask1);