#attributes is not supported by item form elements.

item

Description: Generate a display-only form element allowing for an optional title and description.

Note: since this is a read-only field, setting the #required property will do nothing except theme the form element to look as if it were actually required (i.e. by placing a red star next to the #title).

Properties: #access, #after_build, #description, #element_validate, #parents, #post_render, #prefix, #pre_render, #required, #suffix, #theme, #title, #tree, #type, #value, #weight

You would then need to add a custom theme call such as:

function MYTHEME_preprocess_form_element(&$vars)
{
$vars['#attributes']['class'][] = 'another-class';
}

In the end, I solved it by adding code to the .module file. I wrapped a div with class around the content.

You could use _form_set_class()

Docs: https://api.drupal.org/api/drupal/includes!form.inc/function/_form_set_class/6.x

Example:

_form_set_class($element, array('my-class'));

for the future, if you use the #attributes, wrap the class name(s) in an array like this:

'#attributes' => array('class' => array('myclass', 'otherclass')),


 来自  http://drupal.stackexchange.com/questions/34175/adding-class-to-form-item