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.

{
    "probeId":"1000",
    "mmtId":"A4",
    "nebenprobenNr":"10R1",
    "messdauer":10,
    "fertig":false,
    "geplant":true,
    "messzeitpunkt":"2015-02-09T10:58:36"
}