Apple Logic Pro /LogicExpress Discussion

Hello,
New Logic Express user here...Quick question. I set up my multi-
instruments (external synth modules) in my MIDI instruments  layer in 
the Environment, then cabled them to my associated tracks in my audio 
layer in the Environment. Upon going back to the Arrange window, I 
noticed that my audio tracks have a record button to arm, but none of 
the multi-instrument tracks have that record button. I can play my 
external modules with no problem, but can't figure out why there are 
no record buttons. Did I miss something in the multi-instrument setup 
in the Environment, or something as far back as in Logic Setup 
Assistant. Still scratchin my head! Thanks!