Problems with subnodes in file content conversion

Hi experts,

in a receiver interface I have this mapping:

Header

LIN

    field1

    field2

    PIA

       field2

       field3 

    DTM

       field4

So PIA and DTM are subnodes of LIN (=Lines).

In FCC convertions I have set:

RecordSet Structure = Header,LIN,PIA,DTM

and for each node:

node.fieldSeparator = +

node.endSeparator = 'nl'

The result is:

LIN+00002++11110141A:EN+PIA+1+11120141A:IN

QTY+21:100.000:PCE

My expected result is:

LIN+00002++11110141A:EN

PIA+1+11120141A:IN

QTY+21:100.000:PCE

I don't understand why PIA segment doesn't come in a new line.

Is possible to get my expected result?

Thanks

Fabio