Model admin editor

[mi32dogs]

I cant get the Model admin panel to work, what am i doing wrong?
i have a simple dataobject and model admin file and if i add a model admin panel it list the dataobject but it is not saving it
any hints would be appreciated

DataObject:
`class tester extends DataObject
{

private static $db = array(
    'List' => 'Boolean',
    'Name' => 'Varchar(150)',
);

private static $singular_name = 'tester';
private static $plural_name = 'testers';


public function getCMSFields()
{
    $fields = parent::getCMSFields();
    $fields->addFieldToTab('Root.Main', CheckboxField::create('List', 'List on locations overview page'));
    $fields->addFieldToTab('Root.Main', TextField::create('Name', 'Name'));

    return $fields;
}

}`

Model Admin:
`class testerAdmin extends ModelAdmin
{

private static $managed_models = array(
    'tester'
);

private static $url_segment = 'testers';

private static $menu_title = 'testers';

[mi32dogs]

any body?
or is it a dumb question?