Unable to save settings on "Delivery"

Hello all,
I have installed serviio on DNS-320L. Whatever I configure in Delivery isn't saved.
Here is the log:
I have installed serviio on DNS-320L. Whatever I configure in Delivery isn't saved.
Here is the log:
- Code:
-------------------------------
version : 1.4.7
class[1] : org.serviio.ui.representation.DeliveryRepresentation
path : /delivery/subtitles/embeddedSubtitlesExtractionEnabled
converter-type : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
required-type : org.serviio.ui.representation.SubtitlesRepresentation
class : org.serviio.ui.representation.SubtitlesRepresentation
field : embeddedSubtitlesExtractionEnabled
---- Debugging information ----
2016-03-14 17:58:00,339 WARN [ServiioStatusService] UnknownFieldException occured. Returning error code 500 to the REST layer. Message: No such field org.serviio.ui.representation.SubtitlesRepresentation.embeddedSubtitlesExtractionEnabled