Getting the error 'INS-41104: No Private Interface designated.' during Grid Installation

I'm in the process installing the Grid Infrastructure (two node RAC cluster using virtualbox) but it seems like its not picking up the Private interface due to:

INS-41104: No Private Interface designated. Cause: There is no interface marked as Private.

For the private network I used the default Host-Only Adapter and can ping each other using both public and private network. 

The following is /etc/hosts (which is the same on both node)

127.0.0.1       localhost.localdomain   localhost

# Public

192.168.1.111   ol6-112-rac1.localdomain        ol6-112-rac1

192.168.1.112   ol6-112-rac2.localdomain        ol6-112-rac2

# Private

192.168.56.11   ol6-112-rac1-priv.localdomain   ol6-112-rac1-priv