Melanchthon Misinterpreted Trent?

Here's another Called to Communion tidbit. This little nugget was buried in footnote #6-

When I was seeking Protestant sources and arguments to keep me from converting to Catholicism, I found that this misinterpretation came down to me from the very pen of John Calvin (6)


(6)Apparently Philip Melanchthon also misinterpreted Trent in the same way, but I have not found the source for this assertion.

So why mention Melanchthon? Without documentation, this is called "hearsay", or perhaps "myth".  It reminds me of the Melanchthon letter to Calvin myth that a Romanist source used to bring up.