OK, this has been answered in the JBPatch thread before, but I'll post it here again:
You have originally installed JBPatch before KindCalc came out. So JBPatch has installed an old version of the merged developer keystore, which does not contain the KindCalc developer certificate.
The developer keystore is something that persists "outside" of JBPatch installs, uninstalls, or reinstalls. And it is only reinstalled if it is missing, not if it is (potentially) outdated.
The easiest way to solve your problem is to unregister your Kindle. This will remove the developer keystore. Afterwards, just re-register your Kindle, try to start any Kindlet, and the current developer keystore will be installed. (@icantbebothered: if you keep ignoring my advice to de-register and re-register your device, which definitely works, then soon, icantbebothered to help you out either anymore. I'm now posting this for the third time!)
(and yes, at the risk of repeating myself: this is a prime example of why the well-known test key should be reused, instead of every developer creating their own one, which will need to be individually included in the merged keystore and cause all sorts of problems).
Last edited by ixtab; 10-07-2012 at 10:41 AM.