It's a bit unclear. You want to load _env.ksh into your current script?
If so, you need to source it in your script.
source ./_env.ksh
# or
. ./_env.ksh
If not, there could be a few other reasons, but it's hard to say based on the info you've given.
Can you post the shebang you're using (unless you do plan to source the file, in which case it makes no difference as it's just a comment), and an long listing of the files we're talking about?