Scott Walker Asked If He Knew of $700,000 Mining Co. Payoff: "Not to my knowledge"

Scott Walker, when asked if he was aware of the $700,000 donation the mining company, Gogebic Taconite gave Wisconsin Club for Growth responded with "not to my knowledge." (Milwaukee Journal-Sentinel, September 14, 2014) (Which means exactly what?)

This means Scott Walker is a fraud who cannot be trusted.