Switching groups - not working

[Ian Melnick <dazed@vonsteuben.cps.k12.il.us>]

Hello, everyone

I want certain users to be able to switch into different groups. So I
did a usermod -g/-G on them and checked the group file to make sure it
did it right (and it looks like it did). So then I try out the sg and
newgrp commands. Problem is, these groups don't have passwords. In the
group file, the password field is an 'x', and in the group shadow file
it's a '*'. But when I just press return at the switch group password
prompt, it doesn't accept it.

What am I doing wrong?

Thanks
Ian