Two things.
First, make sure there is a map spot or some thing tagged with 6 in the sector you wish to check.
Second, your if statements are going to do nothing because you don't specify a block for them to follow.
Place your ReplaceTextures lines in braces, like the following:
if(CheckActorFloorTexture(6, "FROFLR4")){
ReplaceTextures("CRASSKY","LIGHSMOU");
ReplaceTextures("MRXSTARS","LIGHCSKY", NOT_MIDDLE);}
Do this for all points when you call "if."
I had a PlantManGrass prop in there
EDIT: I added the braces and it still doesn't work.
EDIT 2: So, I changed the script and I got it to work
if(weather == "snowy")
{
ReplaceTextures("CRASSKY","LIGHSMOU");
ReplaceTextures("MRXSTARS","LIGHCSKY", NOT_MIDDLE);
}
else
{
ReplaceTextures("CRASSKY","LIGHTMOU");
ReplaceTextures("MRXSTARS","BLIZBLU2",NOT_MIDDLE);
}
SetMusic("WTDW1MUS", 0);
}