How To get Instance Name Of SQL Server

I'm Making Report Designer Its generate Report Of all type Of different database Like excel,access,sqlserver, oracle
 
But Problem Is that I'm Fail Getting All Sql Server Instance Name
My code giving only server name like PC name not Instance name like SQL Express
 
here My code

public static SqlDataSourceEnumerator Instance = SqlDataSourceEnumerator.Instance; //Get server Names
public static DataTable Table = new DataTable();
Table = Instance.GetDataSources();

But Its Not Giving Instance Name
what wrong With My Code
Any Another Way To Get SQL Server Instance Name
Please............ Help Me Fast
 

thanks In Advance