I can't register a user on ejabberd with postgresql

Question

Whenever I try adding a new user like:

ejabberdctl register admin localhost default

It gives me the following error:

Problem 'error undef' occurred executing the command.
Stacktrace: [{ejabberd_odbc,escape,["admin"]},
         {ejabberd_auth_odbc,is_user_exists,2},
         {ejabberd_auth,'-is_user_exists/2-fun-0-',3},
         {lists,any,2},
         {ejabberd_auth,try_register,3},
         {ejabberd_admin,register,3},
         {ejabberd_ctl,call_command,3},
         {ejabberd_ctl,try_call_command,3}]

I have erlang with pg library, and set the following configurations on ejabberd:

{auth_method, odbc}.
{odbc_server, {pgsql, "localhost", "ejabberd", "root", "admin"}}.

I also created a database named ejabberd and migrated the pg.sql file. Do I need something else or am I doing something wrong?