newbie compile question. please help

Dear Folks,

Could someone please tell me what I am doing wrong here?

I made some minor changes to
main.c   then
make then
make install

when I want to start the postmaster I get

**************************************************
The program "postmaster" was found by
"/home/gevik/postgres/build2/bin/pg_ctl"
but was not the same version as pg_ctl.
Check your installation.
*************************************************

What am I doing wrong here?

Regards,

Gevik