DotNetNuke Upgrade Error

The Assembly Version ( [ASSEMBLYVERSION] ) does not match the Database Version ( [DATABASEVERSION] )

ERROR: Could not connect to database.

An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)