Unable to connect to SQL instance with SMO via C#

i having situation occur quite odd.  have instance of sql 2008 r2 adventureworks db attached.  if try connect database sqlconnection object, works expected.  need use smo , connection failing when using same connection string.  , mean same - using same const value within same method.  below code, along notation of fails , error message is:

public void testsqlconnection()  {        const string constring = @"integrated security=sspi;data source=maindev\sqlexpress;persist security info=false;initial catalog=adventureworks2008r2";      const string databasename = "adventureworks2008r2";        // first try connect sqlconnection
    sqlconnection conn = new sqlconnection(constring);      try      {          conn.open();          system.diagnostics.debug.write(string.format("via sqlconnection: {0}", conn.state));      }      catch (exception ex)      {          showexception(ex);      }           {          conn.close();      }        // try using smo objects      serverconnection connection = new serverconnection(constring);      server serverinstance = new server(connection);      try      {          // try out database object - error occurs          database db = new database(serverinstance, databasename);      }      catch (exception ex)      {          // showexception method helper displays exception message , recurses down           // inner exception showing each message until there aren't more          showexception(ex);          /*              * initial exception message: setparent failed database 'adventureworks2008r2'.              * inner exception (1): failed connect server integrated security=sspi;data source=maindev\sqlexpress;persist security info=false;initial catalog=adventureworks2008r2.              * inner exception (2): network-related or instance-specific error occurred while establishing connection sql server. server not found or not accessible.            *                          verify instance name correct , sql server configured allow remote connections. (provider: sql network interfaces,            *                          error: 26 - error locating server/instance specified)          */      }  }

the serverconnection constructor not take same connection string sqlconnection takes. serverconnection takes instance name. try:

serverconnection connection = new serverconnection("maindev\sqlexpress");

alternatively can create sqlconnection instance so:

sqlconnection cxn = new sqlconnection(constring); serverconnection serverconnection = new serverconnection(cxn);

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