XML Schema in JAXP1.2

Hi, 

Does anybody have experiences with JAXP1.2?

I am trying to valiidate an instance XML doc according to an XML Schema
using JAXP1.2 .  According to the documentation, JAXP1.2 is supposed to 
support XML Schema. However, I always got the error like "attributes are 
not implemented", when I tried to set any XML Schema such as:

try {
  factory.setAttribute(JAXP_SCHEMA_LANGUAGE, W3C_XML_SCHEMA);
} 
catch (IllegalArgumentException x) {
  // Happens if the parser does not support JAXP 1.2
  ...
} 


I installed both J2SE1.4.2 and JWSDP1.2, and I am using NetBeans to 
develop my programs. 

Do I need to do any further configurations?

Thanks.

Shen