SQLCMD :connect dynamic parameter In SSMS I have this

:SETVAR DBSrvrInst MyDatabase
:connect  ADMIN:$(DBSrvrInst)


In the Messages tab I get 


  Connecting to ADMIN:$(DBSrvrInst)...


The variable isn't being replaced. 
But if I do this and remove the constant

:SETVAR DBSrvrInst MyDatabase
:connect  $(DBSrvrInst)


In the Messages tab I get 


  Connecting to MyDatabase...


The variable is replaced correctly.
How do I get this to work

:SETVAR DBSrvrInst MyDatabase
:connect  ADMIN:$(DBSrvrInst)


I would even be ok with using the port but that doesn't work either

:SETVAR DBSrvrInst MyDatabase
:connect  $(DBSrvrInst),1434


Any suggestions are greatly appreciated.
How about just placing the ADMIN: text in the variable? eg

:setvar DBSrvrInst ADMIN:.\sql2014

:connect $(DBSrvrInst)
GO