Ant build fail - because ant forgets property?!

Question

Hi

I am getting the following build error-

BUILD FAILED 
C:\eclipse\workspace\ContinuousTesting\build.xml:55:
C:\eclipse\workspace\ContinuousTesting\${lib.dir}

Here is the build.properties file:

src.dir=./src 
build.dir=./bin 
lib.dir=./lib

This is the whole task

<target name="compile" depends="properties, create.build.dir, xmlmapping.jar.import" description="Perfom compilation">  
        <!-- Compile the java code -->  
        <echo message="[compile] compiling sources with lib ${lib.dir} to ${build.dir} source dir ${basedir}" />  
        <javac srcdir="${src.dir}" destdir="${build.dir}" listfiles="no" debug="true" classpathref="build.classpath" fork="true" memoryInitialSize="128m" memoryMaximumSize="512m" />  
        <antcall target="backup" />  
</target>  

and it generates the following output

compile:  
    [echo] [compile] compiling sources with lib ./lib to ./bin source dir C:\eclipse\workspace\ContinuousTesting  
    [javac] Compiling 42 source files to C:\eclipse\workspace\ContinuousTesting\bin 

What is my build.classpath I hear you ask....

<path id="build.classpath">
        <fileset dir="${lib.dir}">
            <include name="**/*.jar" />
        </fileset>
        <pathelement path="${build.dir}" />
</path>

I am running this through eclipse.

What am I missing?

Thanks! Azriel