Why won't the White House speak?

Isikoff, via Atrios, has it exactly right:

I think the problem that the White House has is the public statements that they made at the time in which they completely dismissed the notion that Rove or anybody else in the White House had anything to do with the outing of Valerie Plame, totally ridiculous I think was Scott McClellan's line that he gave to reporters.

Now, since, McClellan is refusing to answer any questions, saying we can't talk about it, it's an ongoing criminal investigation. The problem is they already had talked about it, and the question that is being asked is, are those previous statements still operative?