Admin Console access?

Currently working on installing 2x 2013 servers in coxistance with 2007.

I have the MBX role installed as defined, and was going to install the CAS role on the 2nd server next.  I tried looking at the local admin consle and it wont work.  

I have a feeling it wont work until I install the CAS role on the other 2013 server. Am I correct on this?  Just want to make sure before I add another server.

Front end is CAS, back end is MBX roles.

Thanks, Grady Vogt