[gentoo-user] trouble overriding a command name

I know this is trivial and apologize in advance for what must be a simple
(non-gentoo) error on my part.

In /home/gottlieb/bin/dia I have the following
    #!/bin/bash
    /usr/bin/dia --integrated

ls -l /home/gottlieb/bin/dia gives
    -rwxr-xr-x 1 gottlieb gottlieb 38 Aug 28 11:28 /home/gottlieb/bin/dia

echo $PATH gives
    /home/gottlieb/bin/:/usr/local/bin:/usr/bin:/bin:/opt/bin:/usr/x86_64-pc-linux-gnu/gcc-bin/4.8.2:/usr/games/bin

which dia gives
    /home/gottlieb/bin/dia

`which dia`
    correctly starts dia in "integrated" (one window) mode

/home/gottlieb/bin/dia
    correctly starts in integrated mode

/usr/bin/dia
    correctly starts dia in the default (two window) mode

BUT plain
dia
    incorrectly starts dia in the default mode.

What am I missing?

thanks,
allan