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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