CUSTOM CODE - Registration Completed FB

Hi, I need to insert in the custom code a custom Facebook event, the “Registration Completed”.

fbq(‘track’, ‘CompleteRegistration’);

I need to insert the CompletedRegistration only on the page “THANKS”.

I tried to do it on this page, but it’s not working

In klickpages you need to put before and after Completed Registration.
There in Wix too?

I need to raise this campaign, its so important!!!