Magento-1.7 Admin Grids – Can’t Set Default Values for Form Fields

i cant set any default value for textfield or button in my custom admin grid form ,here is my code, iam following http://markshust.com/2012/07/05/creating-magento-adminhtml-grids-simplified tutorial
protected function _prepareForm()
{
$model = Mage::registry('custom_backorder');

    $form = new Varien_Data_Form(array(
        'id'        => 'edit_form',
        'action'    => $this->getUrl('*/*/save', array('id' => $this->getRequest()->getParam('id'))),
        'method'    => 'post'
    ));

    $fieldset = $form->addFieldset('base_fieldset', array(
        'legend'    => Mage::helper('checkout')->__('Backorder Information'),
        'class'     => 'fieldset-wide',
    ));

    if ($model->getId()) {
        $fieldset->addField('id', 'hidden', array(
            'name' => 'id',
        ));
    }  



    $fieldset->addField('User_Id', 'text', array(
        'name'      => 'User_Id',
        'disabled'  => TRUE,

        'label'     => Mage::helper('checkout')->__('UserId'),
        'title'     => Mage::helper('checkout')->__('UserId'),
        'required'  => true,
    ));
    $fieldset->addField('User_Email', 'text', array(
        'name'      => 'User_Email',
        'disabled'  => TRUE,
        'label'     => Mage::helper('checkout')->__('UserEmail'),
        'title'     => Mage::helper('checkout')->__('UserEmail'),
        'required'  => true,
    ));
    $fieldset->addField('Product_Id', 'text', array(
        'name'      => 'Product_Id',
        'disabled'  => TRUE,
        'label'     => Mage::helper('checkout')->__('ProductId'),
        'title'     => Mage::helper('checkout')->__('ProductId'),
        'required'  => true,
    ));
    $fieldset->addField('Product_Name', 'text', array(
        'name'      => 'Product_Name',
        'disabled'  => TRUE,
        'label'     => Mage::helper('checkout')->__('ProductName'),
        'title'     => Mage::helper('checkout')->__('ProductName'),
        'required'  => true,
    ));
    $fieldset->addField('Qty', 'text', array(
        'name'      => 'Qty',
        'label'     => Mage::helper('checkout')->__('Quantity'),
        'title'     => Mage::helper('checkout')->__('Quantity'),
        'required'  => true,
    ));
    $fieldset->addField('Avail_Qty', 'text', array(
        'name'      => 'Avail_Qty',
        'disabled'  => TRUE,
        'label'     => Mage::helper('checkout')->__('AvailableQuantity'),
        'title'     => Mage::helper('checkout')->__('AvailableQuantity'),
        'required'  => true,
    ));

    $fieldset->addField('Flag', 'text', array(
            'name'      => 'Flag',

            'label'     => Mage::helper('checkout')->__('Status'),
            'title'     => Mage::helper('checkout')->__('Status'),
            'required'  => true,
    ));

    $fieldset->addField('submit', 'submit', array(



        'value'     => 'Submit',
        'label'     => Mage::helper('checkout')->__('Submit'),
        'required'  => true
        /*'tabindex'  => 15*/
    ));
    $fieldset->addField('title', 'text', array(
      'label'     => Mage::helper('checkout')->__('Title3'),
      'class'     => 'required-entry',
      'required'  => true,
      'name'      => 'title',
      'onclick' => "alert('on click');",
      'onchange' => "alert('on change');",
      'style'   => "border:10px",
      'value'  => 'hello !!',
      'disabled' => false,
      'readonly' => true,
      'after_element_html' => '<small>Comments</small>',
      'tabindex' => 1
    ));

    ?>

    <?php
        $form->setValues($model->getData());
        //$form->setUseContainer(true);
        $this->setForm($form);
        return parent::_prepareForm();
}