Automatically attach mdf file to DataBase with Admin permission

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C#

I using this code for attach mdf ldf files to sql but it Create an exception.
this exception happen also when I do attach manually but when I start sql
as administrator will be disappear.

SqlConnection myConn = new SqlConnection(@"Server=\SQLEXPRESS;Integrated security=True;Initial Catalog=master");

           string query1 = "select name from sys.databases where name='test'";
           SqlDataAdapter da = new SqlDataAdapter(query1 , myConn);
           DataTable dt = new DataTable();
           myConn.Open();
           da.Fill(dt);
           if (dt.Rows.Count == 0)
           {
              string query2 = " CREATE DATABASE [database_name] ON" +
                   "( FILENAME ='test.mdf' )," +
                   "( FILENAME ='test_log.ldf' )" +
                   "FOR ATTACH ;";
              SqlCommand myCommand = new SqlCommand(query2, myConn);
                   myConn.Close();
                   myConn.Open();
                   myCommand.ExecuteNonQuery();
                   MessageBox.Show("DataBase is Created Successfully", "MyProgram",                     MessageBoxButtons.OK, MessageBoxIcon.Information);

error:
..{"Unable to open the physical file \"test.mdf\". Operating system error 5: \"5(failed to retrieve text for this error. Reason: 15105)\"."}