Drupal validation for nested field element I have written some custom validation for each element in a form. I use the following method to display errors. It automatically highlights the required fields.  

form_set_error('field_athletes_male', 'Athletes Male field is required.'); 


My problem is that there are nested element names like this:

 field_coaching_programme[und][0][field_organisation_delivered_by][und][0][value]


The validation message is shown successfully but the element is not highlighted.
Its working now, code as follows 

form_set_error('field_coaching_programme][und][0][field_organisation_delivered_by', 'Organisation delivered by field is required.');