Credit Suisse’s Spencer Wang says that his review of independent audience data shows that Viacom has a real problem on its hands — it isn’t the victim of a possible Nielsen snafu, as Viacom CEO Philippe Dauman has charged. The analyst cut his ad growth forecast for Viacom’s current quarter in half, to 3%, and shaved 4 cents off his earnings per share estimate, to $1.02, after he concluded that “Nick has lost viewership share to the Disney Channel.” Wang doesn’t let Nielsen off the hook completely.