Field email command throws exception

roo> field email template --class com.springsource.petclinic.domain.Owner
field name mailTemplate
Name required
java.lang.IllegalArgumentException: Name required
    at org.springframework.roo.support.util.Assert.notNull(Assert.java:112)
    at org.springframework.roo.classpath.details.DefaultClassOrInterfaceTypeDetails.<init>(DefaultClassOrInterfaceTypeDetails.java:80)
    at org.springframework.roo.classpath.details.ClassOrInterfaceTypeDetailsBuilder.build(ClassOrInterfaceTypeDetailsBuilder.java:140)
    at org.springframework.roo.addon.email.MailOperationsImpl.injectEmailTemplate(MailOperationsImpl.java:259)
    at org.springframework.roo.addon.email.MailCommands.injectEmailTemplate(MailCommands.java:82)                                         [org.springframework.roo.process.manager [59]] ServiceEvent UNREGISTERING
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)