Fix identification of identifier for error report. Setting it to null if the previous attempt was successfull already obviously was a flaw. Using the wrong key HAUPTPROBEN_NR probably could have been avoided by usage of appropriate constants.

{
    "land.kommentar_p": [{
        "id": 1000,
        "erzeuger": "06010",
        "datum": "2012-05-11 12:01:00",
        "text": "Testkommentar",
        "probe_id": 1000
    }]
}