busybox "applet not found"?

I'm trying a little project on my Droid 4 where i need to mount something.

If i attempt the following from Better Terminal (bash, withr root)
# busybox mount /some/block/device /some/mount/point
It works!

If i run it in a script, it returns:
mount: module not found

Is there some environment stuff i need to include in my script? The script is, essentially, just a collection of the command i need to run, and some error checking. It's essentially a bash script.

Thanks.