Unable to verify DKIM

Hello,

I've been trying to verify my DKIM since yesterday and even after waiting a whole day the website is still unable to verify it.

When i click on verify in the control panel I get this message :

''We are unable to get TXT record for DKIM right now. If you have added the TXT record just now, please wait for 30-45 mins for the changes to propagate and try again.''

Furthermore, when I try to check my key on https://dkimcore.org/c/keycheck I get the message :

This is not a good DKIM key record. You should fix the errors shown in red.

DNS query failed for 'myfitcook._domainkey.myfitcook.com':NXDOMAIN

A public-key (p=) is required

The website is hosted on shopify, i've followed all the instructions and created the TXT in domain settings, please instruct me in how to correct this error.

Thank you in advance.