XML serialization question

hello,
Hopefully I phrase my question correctly. In one of my request I have a datatype which has a few values (e.g A B C D E). some of these values are empty when the request is sent to the web server. In the response, I am supposed to see the same datatype along with some other elements.

I notice that some of the elements that were blank in the request are not present in the response. could it be possible that the way soapUI serializes the response, it omits any elements whose value is null/empty.

I am trying to figure out if the problem is with soapUI or the application code. Hopefully my question made sense.

thanks
Ali