As the others have said, the .ka domain extension does not exist.
It's quite difficult to get a new domain extension approved. ICANN, which accepts applications for making new TLDs, opens this registration process only every few years and it is also quite expensive.
Here's more info on getting your own TLD: https://theaudacitytopodcast.com/afilias-explains-how-to-get-your-own-top-level-domain-tld/
If you're only after domain hacking and are not too particular about the spelling (as long as it sounds the same), then you might want to consider a .ca domain instead.
If you're interested, you can check if your domain hack is still available here:
https://www.marcaria.com/ws/en/domains/canada-domain-registration-ca