Working with slf4j while working with SoapUI api

I am using SoapUI java API to run teststeps/testcases/testsuites.

We have configured SLF4J in out project. Now If I call runTestStepByName() method of TestCaseRunner, SLF4J is stopped working and saying 'attempting to append to closed appender'.Till the time this runTestStepByName() method is called, I am getting every log from SLF4J.Once this method is called all the loggers are getting closed. But If we use normal log4j it is working in all cases. Am I missing something. Is there any thing worng?