make package don't build package

[Alexandr]

I run FreeBSD 5.3
I free my ports tree and make this:

cd /usr/ports/www/audio/mpg123/
make package

and get:
===>  Installing for mpg123-esound-0.59r_15
===>   mpg123-esound-0.59r_15 depends on shared library: esd.2 - found
===>   Generating temporary packing list
===>  Checking if audio/mpg123 already installed
===>   mpg123-esound-0.59r_15 is already installed
      You may wish to ``make deinstall'' and install this port again
      by ``make reinstall'' to upgrade it properly.
      If you really wish to overwrite the old port of audio/mpg123
      without deleting it first, set the variable "FORCE_PKG_REGISTER"
      in your environment or the "make install" command line.
*** Error code 1

Stop in /usr/ports/audio/mpg123.

I don't understand, in bsd.port.mk wrote 
# package		- Create a package from an _installed_ port.
but I  installed this package and wont build package
Why 'make package' make install ???