Rvm wrapper doesn't work when using another gemset

Question

I am creating a rvm wrapper (ftg is the ruby program I wrote):

$> rvm gemset create ftg_gemset
ruby-2.2.3 - gemset created /Users/pinouchon/.rvm/gems/ruby-2.2.3@ftg_gemset

$> rvm wrapper ruby-2.2.3@ftg_gemset ftg
Regenerating ruby-2.2.3@ftg_gemset wrappers........

$> which ftg
/Users/pinouchon/.rvm/gems/ruby-2.2.3@ftg/bin/ftg

$> ftg # command is found. Very cool
Usage: ftg <command> [arguments...]
...

So far so good. But then:

$> rvm gemset use global
Using ruby-2.2.3 with gemset global

$> ftg # command not found. Not cool
zsh: command not found: ftg

I thought rvm wrappers were supposed to allow you to wrap a ruby program as an "executable", and execute if from anywhere (regardless of your current path or gemset). Am I understanding rvm wrappers correctly ?