Error: Using Large Objects by perl5-Interface

I want to use Large Objects in PostgreSQL, source is a Perl-Script. But in
unchained mode it won´t work. What else should I do to change in chained
mode ?

    Users-Guide: "By default, Postgres executes transactions in
unchained mode (also known as "autocommit" in other database systems)."

Source:
      $result      = $conn->exec("BEGIN");
      $stoeroid    = $conn->lo_creat( 'PGRES_INV_ARCHIVE');
      $stoeroidlen = $conn->lo_write( $stoeroid, $Meldung, length(
$Meldung));
      $ERRor       = $conn->lo_close( $stoeroid);
      $result      = $conn->exec("END");

results in Debug-Backend
    query: BEGIN
    ProcessUtility: BEGIN
    CommitTransactionCommand
    StartTransactionCommand
    query: select proname, oid from pg_proc where proname = 'lo_open' or
proname = 'lo_close' or proname = 'lo_creat' or proname = 'lo_unlink'
    or proname = 'lo_lseek' or proname = 'lo_tell' or proname = 'loread'
or proname = 'lowrite'
    ProcessQuery
    CommitTransactionCommand
    StartTransactionCommand
    CommitTransactionCommand
    StartTransactionCommand
    ERROR:  lo_write: large obj descriptor (34850) out of range
    AbortCurrentTransaction
    StartTransactionCommand
    ERROR:  lo_close: large obj descriptor (34850) out of range
    AbortCurrentTransaction
    StartTransactionCommand
    query: END
    ProcessUtility: END
    CommitTransactionCommand

Thanks for help.

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