Runtime error when deploying a JavaFX application

I'm trying to deploy a JavaFX app. The app I've been working on is fairly complex and includes several libraries. When I create a jnlp and try to run it I always get a "Runtime error. Click for details" message. Someone suggested I try doing just a simple Hello World app to see if it's an issue with the included libraries. I tried that and I still get the "Runtime error."

Here's the build.xml I'm trying to use.

    <project name="App" default="default" basedir="." xmlns:fx="javafx:com.sun.javafx.tools.ant">
        <taskdef resource="com/sun/javafx/tools/ant/antlib.xml"
             uri="javafx:com.sun.javafx.tools.ant"
             classpath="C:\Program Files\Java\jdk7\lib\ant-javafx.jar" />


        <target name="default">
        <fx:deploy width="600" height="400" outdir="${basedir}/dist" outfile="App">
            <fx:application name="App" mainClass="${javafx.main.class}"/>

            <fx:resources>
                <!-- include application jars -->
                <fx:fileset dir="${basedir}" includes="*.jar"/>
                <fx:fileset dir="${basedir}/lib" includes="*.jar"/> 
                <fx:fileset dir="${basedir}" includes="app.ini" />
                <fx:fileset dir="${basedir}/template" includes="*.template" />
            </fx:resources>

            <!-- request user level installation -->
            <fx:preferences install="false"/>
        </fx:deploy>
        </target>
    </project>

For the Hello World version I just removed the <fx:resources> section. I run both of them from inside eclipse as an ant task. They both created a dist folder in my project with a .jnlp and a .html file. I then click on the jnlp to run the app and see a small window that has the text, "Runtime error. Click for details.' I click it and get an error window that says, "The application failed to run. Th