[O] Problem with TAB key

[claude fuhrer]

Dear all,

sorry for the probably stupid question, but I have a problem with the 
TAB key. I do not really understand how orgmode process the multiple 
definition of the same key sequence. For a while (if my memories are 
right) I could type "<s" and then TAB to have a block "BEGIN_SRC .. 
END_SRC" or <l for "BEGIN_EXPORT latex". Since a couple of days, this is 
not usable anymore. Instead of replacing the "<s" with the orgmode code, 
TAB just indent what I have typed... The output of "describe-mode" does 
not shows (for me) something that I can use.


I've no idea how to identify the problem and (except a daily update of 
orgmode) I didn't change anything in my configuration. Can you please 
give me some pointer how to identify more precisely the problem ?


I'm using :

Org mode version 9.1.3 (release_9.1.3-175-gd7f2c8 @ 
/home/azubi/bin/local-lisp/org-mode/lisp/)

GNU Emacs 27.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.18.9) of 
2017-11-25


Thank you in advance for your help

claude