rtems build dependency check doesn't seem to work

[Chan Kim]

Hello,
I've started to work with RTEMS recently but when I modify the rtems source (just added prints),
and go to the rtems-build directory and run 'make', the change in the source is not reflected in the execution file.
but when i remove all the files and directorys under the rtems-build directory and do it from rtems-build.sh over,
the change in the source is reflected. This means I have to do this every time I add something to the rtems-source.
(for information, I added a print to rtems-4.10.99-src/cpukit/libnetworking/rtems/rtems_glue.c while analysing rtems-4.10.99-src/testsuites/samples/loopback/init.c )
Of course there's something wrong in the build system(Makefile), but it's too complex for me to anaylize it.
I'm using it on CentOS6.4 and running the sample program (loopback.exe) on QEMU.
Any help will be greatly appreicated.
Chan Kim