ERROR [WsdlTestCase] Failed to create test step for [X]

I get this error "ERROR [WsdlTestCase] Failed to create test step for [X]" when executing my soapui project from Maven (X is my test case name).

Tests work fine from the SOAPUI client software. My Soap-ui.error log is empty.

There doesn't seem to be enough information to let me debug this - I'm guessing there's some dependency I'm missing, but my tests are fairly simple (REST requests with a few assertions on the HTTP response). I assumed the core maven plugin would suffice.

My maven config is as below (I've also included the eviware repository -http://www.eviware.com/repository/maven2/)

<plugin>
            <groupId>eviware</groupId>
            <artifactId>maven-soapui-plugin</artifactId>
            <version>2.0.2</version>
            <executions>
                <execution>
                    <phase>integration-test</phase>
                    <id>soapui-tests</id>
                    <configuration>
                        <projectFile>${basedir}/src/test/resources/MyTestSuite.xml</projectFile>
                        <outputFolder>${basedir}/target/soapui</outputFolder>
                        <junitReport>true</junitReport>
                        <exportwAll>true</exportwAll>
                        <printReport>true</printReport>
                    </configuration>
                    <goals>
                    <goal>test</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

the preceeding messages are :

[DefaultSoapUICore] Missing folder [/var/lib/jenkins/jobs/Build-Mule-Configuration/workspace/ext] for external libraries 2015-07-01 15:10:48,961 INFO
[DefaultSoapUICore] Creating new settings at [/var/lib/jenkins/jobs/Build-Mule-Configuration/workspace/soapui-settings.xml]