Mechanism type DOM not available

hi i am getting following error with jdk 1.5

File licenseFile = null;
		FileWriter fileWriter = null;
		BufferedWriter bufferedWriter = null;
		try {
			// Create a DOM XMLSignatureFactory that will be used to generate
			// the
			// enveloped signature
			XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM");

// Create a Reference to the enveloped document (in this case we are
			// signing the whole document, so a URI of "" signifies that) and
			// also specify the SHA1 digest algorithm and the ENVELOPED
			// Transform.

Reference ref = fac.newReference("", fac.newDigestMethod(DigestMethod.SHA512, null), Collections.singletonList(fac.newTransform(Transform.ENVELOPED, (TransformParameterSpec) null)), null, null);

// Create the SignedInfo
			SignedInfo si = fac.newSignedInfo(fac.newCanonicalizationMethod(CanonicalizationMethod.BASE64, (C14NMethodParameterSpec) null), fac.newSignatureMethod(SignatureMethod.DSA_SHA1, null), Collections.singletonList(ref));

// Create a DSA KeyPair
			KeyPairGenerator kpg = KeyPairGenerator.getInstance("DSA");
			kpg.initialize(512);

the same thing is working fine with jdk 1.6

What could be the reason ? any idea ?

Try this
XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM", new org.jcp.xml.dsig.internal.dom.XMLDSigRI());

inplace of

XMLSignatureFactory fac = XMLSignatureFactory.getInstance("DOM");