Blog templates and creating from the main site

The main site i made Wp multi site which contains all the right pages/plugins/theme setting etc is what i want to copy...
But when i try to get blog template to copy it it says you can't copy the
"Whoops! The blog ID you posted is incorrect. You cannot template the main site. Please go back and try again. (Generated by New Blog Templates)"

How do i get this set up working?