Clay's appearance on "The Late, Late Show with Craig Ferguson" has been canceled. No reason was given for the cancellation.
The unofficial reason from sources is a conflict of interest with Clay performing last night on Jimmy Kimmel Live:
Ferguson was cancelled when the performance was added to Kimmel. It seems you can appear on competing shows within a short period of time but you cannot perform on the competing shows within a short period of time.
Groban or Buble' did Leno and Letterman within the same window but I think it was at least 3 weeks apart so that may give an indication of the gentlemen's agreement/protocol.