I'm working with Instantwp. I installed the plug-in without problems.
I made configuration files. Setting the config file for development site with these parameters:
label = Dev Site
domain = http://127.0.0.1:4001/
web_path = D :/ DES/Web/Local/Marconi-Art/Sitio/InstantWP_4.3/iwpserver/htdocs
db = marconi_art_wp
live = no
The plug-in displays this error message (twice):
This site (127.0.0.1) is not Recognised and You have not set a default config in your sites. Please make sure the domain or domains  parameters are September to 127.0.0.1 for one site, or That One site is set as the default site.
... and is the same if I comment the line "domain = ..."