TreeSet contains and remove not working

Question

I am using a TreeSet in a class that extends AbstractListModel. It seems that the TreeSet.remove() and TreeSet.contains() is not finding the object. If I run the code below, the element is not found (sometimes).
public boolean removeElement(VariableInfo element){
        boolean removed = model.remove(element);
        if(removed){
            fireContentsChanged(this, 0, getSize());
        return removed;
}If I run this code, however, the element is found. (The code below will fail if the uncommented line is used.) Any ideas why this is happening? I don't want to use the code below because it requires iterating over all the elements in the list.
public boolean removeElement(VariableInfo element){
        for(VariableInfo v : model){
            if(v.equals(element)){
                return model.remove(v);
                //return model.remove(element); //will also fail if using this line instead of previous one
        return false;
}

Answer 1

Sorry for the confusion. The compareTo method in VariableInfo simply calls the compareTo method in VariableName which is wrapped by the Variableinfo object. The two classes below should clarify what I mean. Should I not be calling the compareTo method on VariableName from the VariableInfo class?
public class VariableInfo implements Comparable<VariableInfo>{
     * Variable name
    private VariableName name = null;
  public VariableInfo(String name, String label, int type, int dataType, int positionInDb, String subscale){
        this.name = new VariableName(name.trim());
        this.label = new VariableLabel(label.trim());
        this.type = new VariableType(type, dataType);
        this.positionInDb = new Integer(positionInDb);
        this.subscale = subscale;
public int compareTo(VariableInfo o){
        System.out.println("VariableInfo compareTo");
          return this.name.compareTo(o.name);
@Override
public boolean equals(Object o){
        System.out.println("VariableInfo equals");
        return (o instanceof VariableInfo) && (this.compareTo((VariableInfo)o)==0);
public class VariableName implements Comparable<VariableName>{
   @Override
    public boolean equals(Object o){
        System.out.println("VariableName equals");
        return (o instanceof VariableName) && (this.compareTo((VariableName)o)==0);
    public int compareTo(VariableName o){
        System.out.println("VariableName compareTo");
        return this.toString().compareTo(o.toString());
}