I have written a build.xml. But when run with ant it shows following error :

buildfile : build.xml
BUILD Failed
Target 'build' does not exist in the project.



The build file is --:


<project name="alohanhiber" default="build" basedir=".">
<target
name="middlegen"
description="Run Middlegen"
unless="middlegen.skip"
>
<path id="hibernate.classpath">
<fileset dir="C:\gaurav\middlegen-2.1">
<include name="**/*.jar"/>
</fileset>
</path>

<mkdir dir="c:/gaurav/Filters"/>
<taskdef
name="middlegen"
classname="middlegen.MiddlegenTask"
classpathref="hibernate.classpath"
/>
<middlegen
appname="alohanhiber"
prefsdir=""
gui="true"
databaseurl="jdbc:microsoft:sqlserver://gauravrahi;database=Alohanet"
driver="com.microsoft.jdbc.sqlserver.SQLServerDriver"
username="sa"
password="sa"
>
<table name="AlohaLog" />
<table name="DBR" />
<table name="GroupData" />
<table name="Page" />
<table name="PagePrivilegeXref" />
<table name="Privilege" />
<table name="Role" />
<table name="RolePrivilegeXref" />
<table name="UserInfo" />
<table name="UserRoleXref" />

<!-- Plugins -->
<hibernate
destination="c:\gaurav\Filters"
package="${name}.hibernate"
javaTypeMapper="middlegen.plugins.hibernate.HibernateJavaTypeMapper"
/>
</middlegen>
<mkdir dir="c:\gaurav\Filters"/>
</target>

<target name="hbm2java"

description="Generate .java from .hbm files." >

<path id="hibernate.classpath">
<fileset dir="C:\gaurav\middlegen-2.1">
<include name="**/*.jar"/>
</fileset>
</path>
<property name="build.generate.dir" location="C:/gaurav/mapper"/>
<mkdir dir="${build.generate.dir}"/>
<taskdef
name="hbm2java"
classname="net.sf.hibernate.tool.hbm2java.Hbm2JavaTask"
classpathref="hibernate.classpath"
/>
<hbm2java output="${build.generate.dir}" classpathref="hibernate.classpath">
<fileset dir="c:/gaurav/Filters">
<include name="**/*.hbm.xml"/>
</fileset>
</hbm2java>
</target>

</project>

? your target is named middlegen, not build.