I wrote an app and it works fine at my system but when I install at another computer it doesn't work and has this error:

> 
> Unhandled exception has occurred ... 
> 
> 
> 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 Locating Server/Instance Specified)
> 
> 
>