مشکل در باز شدن connection - علت خطای A network-related or instance-specific error occurred

[minanazari]

سلام و وقت بخیر

من می خوام به sql express در visual studio وصل بشم با این کد :

 con.ConnectionString = @"Data Source=AKA30\SQLSERVER ;AttachDbFilename=" + Application.StartupPath + @"library.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True;User Id=admin;Password=;";

           

اما خطای مقابل رو می دهد :
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)"

ممنون می شم راهنمییم کنید خیلی لازم دارم