NAV upgrade from NAV2009R2 to NAV2013

I'm getting an error during a conversion from NAV2009R2 to to NAV2013. When I finished step1 and I want to open the database in NAV2013 in order to convert to NAV2013 it gives me the following error:
'The ? collation is not supported by the Microsoft Dynamics NAV Development'.
The NAV2009R2 database is restored on a SQL 2014 server. My understanding is that NAV2009R2 is compatible with SQL2014.
But could this be related to the SQL Server version or can it be something else? The database is not containing and queries or scripts etc.