Problem with the 'Find_Atom()' function

[zze-PEX SOR balc031 FTRD/DTL/CAE]

Hello,

From a C++ program, I want to use the "Find_Atom()" prolog function.
When I specified "member" as argument, I expected that the function would
return the internal key of the "member" atom but I get "-1" instead!

The function is defined as such:
       
        Find_Atom("member");

I thought the internal key corresponding to the "member" atom was already 
defined in the GNU prolog atom table but It seems that it does not exist!

If I use any predicates like "current_op", "assertz", the function always
returns "-1"!

I was inspired by the example: "recovering the list of operators", available
in the GNU prolog manual (chapter 8.4.3).

In this example, "current_op" is the argument of the "Find_Atom" function.
 -'current_op' is a prolog predicate which seems to be already defined by default
  in the prolog atom table!

  Why 'member' does not defined by default?
  Is there a default prolog atom table already defined?

Could anyone could give me some help?

Thanks in advance

S. C.