The registration code we've sent you is correct and will work. Really. The quick and easy recommendation is: copy and paste the name and code directly from the email we sent you into the registration panel, to avoid typos and other glitches. But if you're still having trouble getting the OK button in the registration panel to enable, read on to find out about the common reasons why.
When you pay by PayPal or Kagi, you will get an email from them with things like a "transaction ID" or an "invoice #"; this is not your registration code. Those things may look like "829552046" or "CBZ5THKD31KP" or "8SU94236A3633680Q"; none of those are your registration code. Your registration code is emailed to you by Stick Software, not by PayPal or Kagi, typically within 24 hours of your payment, often quicker than that, occasionally slower. It will be a two-word phrase like "happy donuts" or "lovely potatoes", and it will be tied to your registration name, listed right above the code in the email; both the name and the code must be entered exactly as given.
If you haven't received your registration code from us, there are various possible reasons and remedies; please see our main registration page for details.
We use the name you gave to PayPal or Kagi when you paid. Often, that name has quirks to it. One common quirk is that it is in all capital letters: "NIELS BOHR" instead of "Niels Bohr". Another is that the name contains accents: "Kurt Gödel" instead of "Kurt Godel". Another is that, for whatever reason, two spaces get introduced instead of one: "Albert Einstein" instead of "Albert Einstein". Another is the inclusion of the middle name: "John Stuart Mill" versus "John Mill" or "John S. Mill" (or, with a punctuation difference, "John S Mill"). And of course your name as entered at PayPal or Kagi might simply be misspelled; you might have entered "Johann Wolfgong von Goethe" instead of "Johann Wolfgang von Goethe" (an understandable error).
All of which is spelled out to make this point as clearly as possible: you must enter your name exactly as it appears in the registration email we send to you. Extra spaces, accents, even typos. Our registration mechanism doesn't know that "G. Galilei" and "Galileo Galilei" are the same, and your registration code will only work for your name as we have it in our records.
So the short answer to how to get your registration code entered properly is: use copy and paste, for both the name and the code. This will avoid the many snares and snags that can catch you if you try to type them in. If the registration email you got says:
Name: Charles Darwin
Code (for iEvolve): hairless apes
then you would select and copy "Charles Darwin" and paste it into the Name field of the registration panel, leaving off the initial "Name: " (being especially careful to leave off the space between the colon and the name), and then select and copy "hairless apes" and paste it into the Code field of the registration panel, leaving off the initial "Code (for iEvolve): " (being especially careful to leave off the space between the colon and the code).
The OK button should now be highlighted; if it is not, cancel out of the panel and try again; you probably brought along a stray space or end-of-line character that should not have been there.
All of this has proved much more complicated for users than we expected, which is why we're putting up this page. We are considering a scheme wherein the user could select the text of their registration email and simply drag-and-drop that text, in its entirety, into the registration panel of one of our apps to complete the registration process. We're not sure whether the ability to do this would make things less confusing or more, however. Anyway, until then, we hope the above clarifies things.