Not able to Restore database from specified path in C# (SMO)

[user0019]

trying to restore database as below

private void button1_Click(object sender, EventArgs e)
{
StreamWriter writer = new StreamWriter(@"\servernamevnscript_output.txt", false);
Server s = new Server("servername");
Database Database = s.Databases["ReportServer"];

// Set up the scripting options to be used below.
ScriptingOptions so = new ScriptingOptions();
so.Permissions = true;
so.Indexes = true;
so.IncludeIfNotExists = true;

// First script the database itself
StringCollection coll = Database.Script(so);
foreach (string str in coll)
{
writer.WriteLine(str);
}

//Restore Database
Server srv = new Server("servername");
//Database Database = srv.Databases["Databasename"];
Restore res = new Restore();
res.Database = "ReportServer";
// Set the backup device from which we want to restore, to a file
// BackupDeviceItem bkpDevice = new BackupDeviceItem(@"\ServernamevnReportServer.ba k", DeviceType.File);
res.Devices.AddDevice(@"\ServernamevDatabasenam e.bak", DeviceType.File);
res.Database = "ReportServer";
// res.Database = @"\servername1vn" + "ReportServer.mdf";
res.Action = RestoreActionType.Database;
res.PercentCompleteNotification = 10;
res.ReplaceDatabase = true;
res.PercentComplete += new PercentCompleteEventHandler(ProgressEventHandler);
res.SqlRestore(srv);

writer.Flush();
writer.Close();

}

static void ProgressEventHandler(object sender, PercentCompleteEventArgs e)
{
Console.WriteLine(e.Percent.ToString() + "Restored");
}
}
}

Getting error @line res.SqlRestore(srv);
{"System.Data.SqlClient.SqlError: Directory lookup for the file "C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\ReportServer.mdf" failed with the operating system error 2(The system cannot find the file specified.)."}

I guess its going to the defalut backup drive and searching instead of searching from defined path (@"\ServernamevDatabasename.bak", DeviceType.File)

when i try to restore database from default drive it works fine , but i need to specify the path from where it has to restore

Thanks