Please make sure you have read the Tag Syntax document and understand how tag attribute syntax works.
To use the datetimepicker that you need to include the head tag in you page, and set it theme attribute to "ajax", like
<s:head theme="ajax" />
Description
Error formatting macro: snippet: java.lang.NullPointerException
Parameters
Error formatting macro: snippet: java.lang.NullPointerException
Examples
Error formatting macro: snippet: java.lang.NullPointerException
Error formatting macro: snippet: java.lang.NullPointerException
Error formatting macro: snippet: java.lang.NullPointerException