I need to find what data causes the assertion to fail. I would like to write the data to a file.

Here is my test case:

DataSource, DataGen, SOAP Request, and DataSource Loop

I start the test case, I read data from csv file using Datasource, for every value I call SOAP web service in my test case.  On the soap request I added assertions to ensure I am getting valid expected data on the soap response.  When any of the assertion fails I would like to record the value I used in the SOAP request that caused it. 

I hope this helps

Thanks