Help with Flex Ant build.xml error

Question

So I've started on a new project and I'm new to Flex. A lot of learning curve here. Anyway, I'm trying to deploy a project that uses flex and is built with Ant. We've moving up from a version of Flex 2 to Flex 3. The build file works fine in the Flex 2 app but for some reason does not seem to be working with Flex 3. I'm hoping someone can give me some insight on what might be wrong or where to start.
The error is Command not found: compc
The part of the build file it has a problem with is:
<compc include-classes="${classes}"
     ouput="${flex.dist.dir}/${flex.app.name}.swc"
     keep-generated-actionscript="false"
     headless-server="${headless.server}"
     incremental="true">
<load_config filename="${FLEX_HOME}/frameworks/flex-config.xml" />
<source-path path-element="${FLEX_HOME}/frameworks" />
<source-path path-element="${flex.app.root}" />
<compiler.library-path dir="${FLEX_HOME}/frameworks" append="true">
     <include name="libs" />
     <include name="../bundles/{local}" />
</compiler.library-path>
<compiler.library-path dir="${flex.app.root}" appent="true">
     <include name="libs" />
</compiler.library-path>
</compc>
Any help at all would be greatly appreciated, thank you.

Answer 1

Sorry, I meant to address that. Yes, since we've moved up to the Flex 3 sdk, we are pointing at a new directory. The old directory was flex_sdk and the new directory is flex_sdk_340.
FLEX_HOME is being set in the build.properties file for local building and then overidden in the build.xml file with this code:
<target name="build">
     <available property="FLEX_HOME" value="/apps/flex_sdk_340" file="/apps/flex_sdk_340" />
     <echo>FLEX_HOME = ${FLEX_HOME}</echo>
     <antcall target="compile" />
</target>
I did notice a warning about not using the available property, so I removed it and just changed what FLEX_HOME was set to in the build.properties file to the server directory. Would mess up local building but regardless it didn't matter because it had no effect on the error being generated. I alos looked a little into the file property of the available tag trying to figure out if that was somehow an issue but I wasn't able to come to any conclusion.
Before the program errors out, it does displayt he echo statement and the value of FLEX_HOME appears to be correct in that it does show /apps/flex_sdk_340.
Thank you so much for your continued help. This is truly frustrating because nothing but a directory name has really changed and yet it stopped working. I can't find any information anywhere on what could be wrong and this is really my last resort.