Sharepoint 2013 server backup fails?

Hello Community

    In this scenario SQL Server is installed on WS2012 ServerA.

    Later on SQL Server is move to WS2012 ServerB.

    When the farm is backed up using the Wizard an error appears and when I go to spBackup.Log
I see that following:

[5/27/2015 12:38:48 PM] Verbose: [BusinessDataCatalogDB] SQL Server Connection String: Data Source=ServerA\myServer;Initial Catalog=BusinessDataCatalogDB;Integrated Security=True;Enlist=False;Pooling=True;Min Pool Size=0;Max Pool Size=100;Connect Timeout=15.

something something something ...

[5/27/2015 12:39:03 PM] FatalError: [BusinessDataCatalogDB] A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

    It looks like WS2012 fails because it thinks the SQL Server is still on
ServerA but actually it was moved, and is now on ServerB.

    If that is the case how do I make the backup know that SQL Server is now on ServerB
and if that is not the case what do I have to do to make the backup succeed?

    Note: For testing purpose everything is on "one" server except the Domain Controller and 
             oddly enough most of the other backups succeeded.

    Thank you
    Shabeaut