fileset failed with id attribute

[Кирин Евгений Николаевич]

Hello!
Please help me to resolve error while running Ant.

I've got simple build script:

<project>
 <target name="test">
  <echo>Hello World</echo>
 </target>

 <fileset dir="${basedir} " id="somename">
        <include name="dom3-xercesImpl.jar" />
        <include name="dom3-xml-apis.jar" />
                </fileset>
</project>

When this script is executing I always get error:

BUILD FAILED
java.lang.NoSuchMethodError: org.apache.tools.ant.util.FileUtils.getFileUtils()L
org/apache/tools/ant/util/FileUtils;
        at org.apache.tools.ant.taskdefs.optional.dotnet.ImportTypelib.<clinit>(
ImportTypelib.java:48)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:141)
        at org.apache.tools.ant.AntTypeDefinition.getTypeClass(AntTypeDefinition
.java:161)
        at org.apache.tools.ant.AntTypeDefinition.getExposedClass(AntTypeDefinit
ion.java:135)
        at org.apache.tools.ant.ComponentHelper.getElementName(ComponentHelper.j
ava:577)
        at org.apache.tools.ant.Project.getElementName(Project.java:1769)
        at org.apache.tools.ant.IntrospectionHelper.getElementName(Introspection
Helper.java:1087)
        at org.apache.tools.ant.IntrospectionHelper.setAttribute(IntrospectionHe
lper.java:513)
        at org.apache.tools.ant.RuntimeConfigurable.maybeConfigure(RuntimeConfig
urable.java:368)
        at org.apache.tools.ant.RuntimeConfigurable.maybeConfigure(RuntimeConfig
urable.java:322)
        at org.apache.tools.ant.UnknownElement.configure(UnknownElement.java:191
)
        at org.apache.tools.ant.UnknownElement.maybeConfigure(UnknownElement.jav
a:158)
        at org.apache.tools.ant.Task.perform(Task.java:363)
        at org.apache.tools.ant.Target.execute(Target.java:341)
        at org.apache.tools.ant.helper.ProjectHelper2.parse(ProjectHelper2.java:
133)
        at org.apache.tools.ant.ProjectHelper.configureProject(ProjectHelper.jav
a:91)
        at org.apache.tools.ant.Main.runBuild(Main.java:658)
        at org.apache.tools.ant.Main.startAnt(Main.java:188)
        at org.apache.tools.ant.launch.Launcher.run(Launcher.java:257)
        at org.apache.tools.ant.launch.Launcher.main(Launcher.java:104)

If to remove "id" attribute from "fileset" element then everything is good.

I use ant 1.7.1 and java 6

What could it be?

Thanks for your responses!