The below code works for me,

    $banks = array(14=>"bank one", 22=>"bank two);
I then want to construct a simple select form element, this WILL NOT work:

    $form['drop'] = array(
    #id' => "bank_drop",
    '#type' => 'select',
    '#title' => 'test',
    '#options' => $banks,
    '#default_value' => 22  // will NOT work!
    );

But this works:

    $form['drop'] = array(
    #id' => "bank_drop",
    '#type' => 'select',
    '#title' => 'test',
    '#options' => $banks,
    '#value' => 22  // works!
    );

The problem is is value cannot be changed !!!

This was on Drupal 6.15
for more [here](http://www.givegoodweb.com/post/132/drupal-select-list-default_value)