declare external function NAME_BY_IP
    cstring(32),
    cstring(128) by descriptor
    returns parameter 2
entry_point 'NameByIp' module_name 'IP.dll';

select NAME_BY_IP( '127.0.0.1' )
  from RDB$DATABASE

Invalid token.
invalid request BLR at offset 39.
function NAME_BY_IP is not defined.
module name or entrypoint could not be found.
---------------------------------------------
SQLCODE: -104
SQLSTATE: 39000
GDSCODE: 335544343

declare external function NAMEBY_IP
    cstring(32),
    cstring(128) by descriptor
    returns parameter 2
entry_point 'NameByIp' module_name 'IP.dll';