Domain access mailchimp_api_key

I installed Mailchimp and Domain Access.

There are 2 users:

• admin
• user 1

And there are 2 websites:

• www.example.com (default domain)
• user1.example.com

With admin, I can define Mailchimp Api key at http://www.example.com/admin/config/services/mailchimp:

• If I define Api Key 1 for default domain, value is recorded in variable table
• If I define Api Key 2 for user1.example.com, value is recorded in domain_conf table

For me this is perfect, each domain has got his own Api Key.

But...

If I go on http://user1.example.com/admin/config/services/mailchimp with user1, I can set Api Key without choosing domain because user1 only have domain access to user1.example.com.

When I define Api Key 3 for this user, the value is recorded in variable table, and when form is refreshing, the api key 2 is coming back.

So on the page http://www.example.com/admin/config/services/mailchimp the api key is the api key 3
On the page http://user1.example.com/admin/config/services/mailchimp the api key is the api key 2

It should be:

• Api Key 1 for default domain
• Api Key 3 for user1.example.com

So what's wrong ?
I gave user1 the administrer mailchimp permission, so maybe there is another way ?

Thanks a million