SVN Diff of an Added file while specifying the file name -

There are some related questions on this, as well as many bug reports sprinkle on Google searches, but - new-file or force Or - Anotis-ancestors have not worked for me.

The file is not binary and I want to do some work of work:

  Svn diff -r XXXXXX TestHelloWorld.java  

Where TestHelloWorld.java is an additional file. Currently I'm unable to find a "repo location ..." and I've checked the number of revisions many times (I can get merge changes to show correctly)

Anyone idea?