Unable to send invitation for bonus mailbox

Unable to send invitation for bonus mailbox

Dear Helper,
whenever I try to invite someone for bonus mailbox for my domain (gdllava.com); it says: 
"You can start referring other domains only after you change the mx records of your domain" 

But I'm pointing to mx.zohomail.com and  mx2.zohomail.com since yesterday. And I'm able to send/receive mails from exiting mail accounts. What's the problem?

Please fix the issue and let me avail bonus mailbox at your earliest. Because if I can't create sufficient email accounts for this domain by tomorrow; then I'll be in trouble and may not be able to continue to Zoho.

Please help.  Thanks.

Rana (+8801711524824)