Locale

Why does this happen?

When I logged in from my laptop to nameserver and ran nsvi, I got the following message:

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = "en_US:en",
        LC_ALL = (unset),
        LC_MEASUREMENT = "nl_NL.UTF-8",
        LC_PAPER = "nl_NL.UTF-8",
        LC_MONETARY = "nl_NL.UTF-8",
        LC_NAME = "nl_NL.UTF-8",
        LC_ADDRESS = "nl_NL.UTF-8",
        LC_NUMERIC = "nl_NL.UTF-8",
        LC_TELEPHONE = "nl_NL.UTF-8",
        LC_IDENTIFICATION = "nl_NL.UTF-8",
        LC_TIME = "nl_NL.UTF-8",
        LANG = "en_US.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_US.UTF-8").

But when I login from my normal computer, this does not happen.

During the search of a solution I found it was easy to trigger by using a simple perl command:

perl -e exit