'textfield', '#title' => 'User name of adminstrator', '#description' => t('The user to whom notifications of affiliate registrations will be sent'), '#size' => 16, '#default_value' => $admin, ); return system_settings_form($form); } function affiliate_admin_settings_validate($form, $form_state) { $username = $form_state['values']['affiliate_admin_username']; if ($user = user_load(array('name' => $username))) { variable_set('affiliate_admin_username',$username); } else { form_set_error('affiliate_admin_username', t('Must be the name of a valid user')); } return; }