Saml security signature SHA256 invalid url with "org.opensaml.xml.signature" package

I am using "org.opensaml.xml.signature" package (under xmltooling-1.4.4.jar) with SignatureConstants.ALGO_ID_SIGNATURE_RSA_SHA1. I would like to allow some users to use SignatureConstants.ALGO_ID_SIGNATURE_RSA_SHA256 if they wish.

ALGO_ID_SIGNATURE_RSA_SHA1 produce the url http://www.w3.org/2000/09/xmldsig#rsa-sha1 which leads to valid XML. ALGO_ID_SIGNATURE_RSA_SHA256 produce the url http://www.w3.org/2001/04/xmldsig-more#rsa-sha256 which leads to some invalid page.

Am I using a wrong parameter for sha256?

Thanks, Mike