Can't find the selection for Domain (multisite) support

The site is working on a mobile if I use m.mysite.com but if I use mysite.com the mobile doesn't recognize that it is a mobile device - I just get the regular site on the mobile and it doesn't redirect. I have created and entered the subdomains - m.mysite.com for all. But I can't find the selection for Domain (multisite) support. I am using Joomla 1.5.26 and MJ 1.1.0

To be more clear. I think this option for Domain (multisite) support is missing somehow. I think this is the missing link as to why my mobile site is not detecting that is should forward to the subdomain... And I have all the plugins for MJ enabled.

Me too. The instructions in this forum (www.mobilejoomla.com/forum/10-subdomains/6219-few-bits-of-information-on-subdomains-and-design.html) say to select the option "Domain (multisite) support" but I cannot find that option on my install either.

Has that field been removed in newer versions?

Regardless, I too cannot get redirect to work for my site.