writing empty data to data sink

Hi,

I am trying to write the output of a test case to the 'File' data sink.
I have managed  to setup a property Xfer and the fields are written to the sink.

however, if the element is empty, then its XML name/stuff gets written to the sink instead of a empty string.

I have enclosed a sample output here.

Secondly, What do I need to do if I want to write out the response time of each req-resp pair to the data sink. Which property do i use. I see this information being logged into the SOAPUI log.

I need the response time data for statistical reasons attached to each input data.

I have a Pro version.

Thanks,
Bhuvan.