ComboBox as user input *FAIL* - WHY!!!

Question

private JComboBox comboGender;   
private String sex[] = {"Select Gender", "male", "female"};   
  comboGender = new JComboBox (sex);   
  comboGender.setMaximumRowCount(3);   
  jPanel1.add(comboGender);    
private String getData(JTextField component) {   
     String text, trimmed;   
     if(component.getText().length() > 0) {     
         text = component.getText();        
         trimmed = text.trim();      
         return trimmed;      }
     else {     
         text = "";           
         return text;     
  public void retrieveData(){      
     this.name = getData(jTextFieldName);     
     this.add = getData(jTextFieldAdd);      
     //this.sex = getData(jTextFieldGender);      
     this.phone = getData(jTextFieldPhone);     
     this.mail = getData( jTextFieldEmail);         
  protected void createCustField(boolean readonly, String name, String email,String mail, String phone, String sex){       
      if (readonly == true)             
      jTextFieldName.setEditable(false);       
      jTextFieldEmail.setEditable(false);                     
      jTextFieldAdd.setEditable(false);            
      comboGender.setEditable(false);             
      jTextFieldPhone.setEditable(false); 
  void jButtonAdd_actionPerformed(ActionEvent e) {        
       retrieveData();        
       String sex = (String)comboGender.getSelectedItem();    
       try{            
           custID = customer.createCustomer(name, add,  
                                            mail,phone,sex);     
        } catch (Exception ex){  
          System.out.println(ex.toString());        
       boolean readonly = false;        
       createCustField(false, null, null, null, null,null);
       jTextFieldId.setText(custID);  }after i have changed the code accodring to DerfBergler.. i still get the same error from both the server and client app compiler.
error is :
java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.ServerException: EJBException:; nested exception is:
javax.ejb.EJBException: createCustomer: ejbCreate: General error, message from server: "Column 'custPhoneNo' cannot be null"; nested exception is:
javax.ejb.EJBException: ejbCreate: General error, message from server: "Column 'custPhoneNo' cannot be null"
p/s: before i treat the gender as jTextField instead of combobox. there is no error

Answer 1

this time i have done an experiment since i cant get comboBox working and the message displayed was :
javax.ejb.EJBException: createCustomer: ejbCreate: General error, message from server: "Column 'custPhoneNo' cannot be null"; nested exception is:
javax.ejb.EJBException: ejbCreate: General error, message from server: "Column 'custPhoneNo' cannot be null"i tried treating the gender as text field and manually enter string myself. as it is, te program works. then i tried leaving the field 'gender' empty, the same message is displayed when i changed the gender to combo box instead of text field.
i am sure that there isnt any problem with the db, or the storing part of my coding. i m sure that the problem lies in the combo box does not get the user input at all.
my question is: where have i made my mistake??