I have done some googling but did not get a realy solution. We are in co-existance starting migration process from 2010 to 2013, but with some of the database created in 2013 when trying to migrate the users I get that error message. NOT all on the databases created give that error message but some of them give that error. Running the command "C:\>Get-MailboxDatabase | FT Name,IsExcludedFromProvisioning,IsSuspendedFromProvisioning" all database Show FALSE, so why do some give the above error message.

How can I solve this issue ? the database are in a DAG, 1 active, 1 passive and 1 Lag.

Try this

Set-MailboxDatabase (your db name) -IsSuspendedFromProvisioning:$true

and then run new-moverequest

You can refer to this informative article that elaborate this concern in depth and helps to sort-out this weird issue : http://exchangeserverpro.com/unable-move-mailboxes-exchange-server-2013-database-excluded-provisioning/

Additionally, you may also consider using this automated solution(http://www.exchangemailboxmigration.com/) that could be a good alternative choice while need to migrate users mailboxes from exchange 2010 to 2013.