Transform NullPointerException

[Bill Speirs]

I'm trying to apply a DSA signature to the XML output of a JAXB object
by following this example: http://goo.gl/vVNxy. I'm able to convert
the JAXB object to a Document; however, when I go to create the
XMLSignature I'm unsure what BaseURI I should use as my XML is not
coming from a file like in the example.

The real problem though is that when I attempt to add a Transform, I
keep getting a NullPointerException on this line:
transforms.addTransform(Transforms.TRANSFORM_C14N_WITH_COMMENTS);

Exception in thread "main" java.lang.NullPointerException
        at org.apache.xml.security.transforms.Transform.getTransformSpi(Unknown 
Source)
        at org.apache.xml.security.transforms.Transform.<init>(Unknown Source)
        at org.apache.xml.security.transforms.Transform.getInstance(Unknown 
Source)
        at org.apache.xml.security.transforms.Transform.getInstance(Unknown 
Source)
        at org.apache.xml.security.transforms.Transforms.addTransform(Unknown 
Source)
        at test.Test.main(Test.java:64)

I have attached my source example file and the associated XSD file I
used to generate the Token & Principal JAXB objects.

Any help or insight would be greatly appreciated.

Thanks in advance...

Bill-

Test.java
Description: Binary data

token.xsd
Description: Binary data