Multi-language multisite

Good day

I've setup drupal multisites and I'm using the i18n module for different languages on one of these sites. It works if i use a prefix to switch between the languages but if I use two different domains it's not working. The setup looks like this:

maindomain.com
- subsite1.com (subsite1.com = default language. subsite1-za.com points to this folder (different language) - should it rather be a sub-domain?)
- subsite2.com

Please help. What am I missing here?

Thanks.