JUNG loading grpah question

i get this error when i try to load the graph from the text file

java.io.IOException: specified 'source' attribute "A" does not match any node ID
at edu.uci.ics.jung.io.GraphMLReader.parse(GraphMLRea der.java:246)
at edu.uci.ics.jung.io.GraphMLReader.load(GraphMLRead er.java:192)
at hyperGraph.loadGraph(hyperGraph.java:189)
at hyperGraph.main(hyperGraph.java:233)

here is my loading graph code

Code java:

class VertexM {
        String name = "";
 
 
        public VertexM() {
        }
 
        public VertexM(String name) {
                this.name = name;
        }
 
        public String toString() { 
                return name; 
        }
 
        public boolean equals(Object obj) {
                if (obj == this) {
                        return true;
                }
 
                if (obj == null) {
                        return false;
                }
                VertexM other = (VertexM) obj;
 
                boolean a = this.getName().equals(other.getName());
                return a;
        }
 
        public void setName(String name) {
                this.name = name;
        }
 
        public String getName() {
                return name;
        }
 
        public int getCount() {
                return 1;
        }
 
        public int hashCode() {
                return name.hashCode();
        }
}
 
class EdgeM {
        float count;
        String id = "";
 
        public EdgeM() {
                this.count = 0;
        }
 
        public EdgeM(String d, String v1, String v2) {
                this.id = v1 + v2;
                this.count = Integer.parseInt(d);
        }
 
        public String toString() { // Always good for debugging
                return id;
        }
 
        public void addCount() {
                count++;
        }
 
        public void setId(String id) {
                this.id = id;
        }
 
        public float getCount() {
                return count;
        }
 
        public boolean equals(Object obj) {
                if (obj == this) {
                        return true;
                }
)
                if (obj == null) {
                        return false;
                }
                EdgeM other = (EdgeM) obj;
 
                boolean a = this.toString().equals(other.toString());
                return a;
        }
 
        @Override
        public int hashCode() {
                int result = Math.round(count) * 37 + id.hashCode();
                return result;
        }
}
 
 
public static UndirectedSparseGraph<VertexM, EdgeM> loadGraph(Reader reader) {
                class EdgeMFactory implements Factory<EdgeM> {
 
                        @Override
                        public EdgeM create() {
                                return new EdgeM();
                        }
 
                }
 
                class VertexMFactory implements Factory<VertexM> {
                        public VertexM create() {
                                return new VertexM();
                        }
 
                }
                GraphMLReader<UndirectedSparseGraph<VertexM, EdgeM>, VertexM, EdgeM> graphReader =
null;
                try {
                        graphReader = new GraphMLReader<UndirectedSparseGraph<VertexM, EdgeM>, VertexM,
EdgeM>(
                                        new VertexMFactory(), new EdgeMFactory());
                } catch (ParserConfigurationException e1) {
                        e1.printStackTrace();
                } catch (SAXException e1) {
                        e1.printStackTrace();
                }
 
                UndirectedSparseGraph<VertexM, EdgeM> fixGraph = new
UndirectedSparseGraph<VertexM, EdgeM>();
                try {
                        graphReader.load(reader, fixGraph);
                        Map<String, GraphMLMetadata<VertexM>> nodeMetaData = graphReader
                                        .getVertexMetadata();
 
                        for (VertexM node : fixGraph.getVertices()) {
                                String nodeName = ((String)
(nodeMetaData.get("NodeName").transformer.transform(node)));
                                System.out.println("NODE" + nodeName);
 
                                node.setName(nodeName);
                        }
 
                } catch (IOException e) {
                        e.printStackTrace();
                }
 
                return fixGraph;
        }
 
        /**
         * @param args
         * @throws SAXException
         * @throws ParserConfigurationException
         */
        public static void main(String[] args) {
 
                  try { FileReader in = new FileReader(
                  "C:\\Program Files\\Eclipse for FYP\\output\\test.txt"); 
                  Hypergraph<VertexM, EdgeM> hg = loadGraph(in);
                  System.out.println(hg.getVertices()); } catch
                  (ArrayIndexOutOfBoundsException e) {
 
                  System.out.println("Usage: java ReadFile filename\n");
 
                  } catch (IOException e) { e.printStackTrace(); }
}

my save file is

Code :

<?xml version="1.0" encoding="UTF-8"?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns/graphml"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns/graphml">
<key id="NodeName" for="node">
<desc>File Name</desc>
<default></default>
</key>
<key id="EdgeName" for="edge">
<desc>Edge Visit Name</desc>
<default></default>
</key>
<key id="EdgeCount" for="edge">
<desc>Edge Visit Count</desc>
<default></default>
</key>
<graph edgedefault="undirected">
<node id="A">
<data key="NodeName">A</data>
</node>
<node id="B">
<data key="NodeName">B</data>
</node>
<node id="C">
<data key="NodeName">C</data>
</node>
<edge source="A" target="C">
<data key="EdgeName">AC</data>
<data key="EdgeCount">3.0</data>
</edge>
<edge source="A" target="B">
<data key="EdgeName">AB</data>
<data key="EdgeCount">2.0</data>
</edge>
</graph>
</graphml>

is there any problem for my code?