Additional META-INF files don't find the way into the jar. 

Use following ANT target to fix the problem:

<target
depends="init,-uno-project-init,uno-idl-compile,-jar-idl-types,compile,-pre-jar,-do-jar-with-manifest,-do-jar-without-manifest,-do-jar-with-mainclass,-do-jar-with-libraries,-do-openoffice-manifest,-really-do-jar,-post-jar"
name="jar"/>
    <target name="-really-do-jar">
        <jar basedir="${build.classes.dir}" update="true" compress="true"
excludes="**/*.xml,**/*.txt,${idl.file.list},${build.classes.excludes}"
filesonly="true" jarfile="${dist.jar}" manifest="${build.dir}/MANIFEST.MF"/>
    </target>