postgres createdb invalid locale name debian

$ sudo -u postgres createdb -l th_TH.UTF-8 -E UTF-8 -T template0 mydb;
createdb: database creation failed: ERROR:  invalid locale name th_TH.UTF-8

$ locale -a
C
en_US.utf8
POSIX

$ sudo apt-get install locales

$ sudo dpkg-reconfigure locales
# in debian this command will display a screen while ubuntu not!!

$ sudo init 6

$ locale -a
C
en_US.utf8
POSIX
th_TH.utf8



Useful cmd
=======
$ sudo locale-gen th_TH.UTF-8
$ sudo locale-gen --purge en_US.UTF-8 th_TH.utf8


$ sudo apt-get install locales-all