build package of already installed packages fails

[netbsd-users%rmroppert.info@localhost]

Hello

i want to create packages of already installed packages:

As described in the pkgsrc guide (Appendix B.1 and B.2) i do:

-->make
-->make install
or
-->make update

Then if i do
--> make package
i always get the error
" ... already installed - perhaps an older version?
...
make stopped.

Isn't it possible to build an package of an an already installed
package or is there another way to do this?

Regards
Reinhold