Problem with database link from Oracle to Postgres

Hello

I have crated a dblink between Oracle 12c r1 to postgres 14 and I have the following error while executing a query µ:

[Error] Execution (8: 36): ORA-28500: connection from ORACLE to a non-Oracle system returned this message:

ERROR: current transaction is aborted, commands ignored until end of transaction block;

No query has been executed with that handle {25P02,NativeErr = 1}

ORA-02063: preceding 3 lines from PG_DBLINK_SP

The connection with isql works fine

+---------------------------------------+

| Connected!               |

|                     |

| sql-statement              |

| help [tablename]            |

| quit                  |

|                     |

+---------------------------------------+

SQL>

thanks in advance for your help