my wallet says that:
checkpoint is too old. wait for block chain to download, or notify developers
in the meantime... staking like hell

Yes, I had that same issue. I imagine you are running wallet 1.5.5.0 or 1.5.6.0? I reverted back to running wallet 1.5.2.0 as there were some other issues that I couldn't resolve. It works fine and yes, I to am staking awesomely!!! Can't wait for the next news from DEV. Things are finally falling into place. Online wallet, marketplace, KTK to USD exchange, and over a year old now..........what else needs to happen for KTK to take off?