This is the SoapUI error log. I use the QCRest class for Selenium so I know it works fine. It seems to be a Soap Groovy script issue.
Tue Dec 01 12:00:12 CST 2015:ERROR:java.lang.NoClassDefFoundError: java/util/Base64
java.lang.NoClassDefFoundError: java/util/Base64
at qcrestapi.QCRest.QCLogin(QCRest.java:139)
at qcrestapi.QCRest.QCLogin(QCRest.java:115)
at qcrestapi.QCRest$QCLogin.call(Unknown Source)
at Script13.run(Script13.groovy:4)
at com.eviware.soapui.support.scripting.groovy.SoapUIGroovyScriptEngine.run(SoapUIGroovyScriptEngine.java:92)
at com.eviware.soapui.impl.wsdl.teststeps.WsdlGroovyScriptTestStep.run(WsdlGroovyScriptTestStep.java:141)
at com.eviware.soapui.impl.wsdl.panels.teststeps.GroovyScriptStepDesktopPanel$RunAction$1.run(GroovyScriptStepDesktopPanel.java:250)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)