Unable to add apps to sharepoint 2013 tenant site

Hi,

When I try to open SharePoint store with tenant site i get error "Sorry, apps are turned off. If you know who runs the server, tell them to enable apps." It works fine with normal site.

Steps tried so far:

1. Added "APP management service application" to teant service application group

2. Make sure it is working fine for normal sites

3. Created appropriate DNS entry

Quick reply would be appreciated

Regards,

Inderjeet