How to restore a database from C#

I have a SQL 2008 DB. I am running a form that backs that DB up, then tries to update it. If the update fails the idea is to restore that backup. Here is the code I am using to restore the backup.

public void RestoreDatabase(String databaseName, String backUpFile, String serverName, String userName, String password)
{
    Restore sqlRestore = new Restore();
    BackupDeviceItem deviceItem = new BackupDeviceItem(backUpFile, DeviceType.File);
    sqlRestore.Devices.Add(deviceItem);
    sqlRestore.Database = databaseName;
    ServerConnection connection = new ServerConnection(serverName, userName, password);
    Server sqlServer = new Server(connection);
    sqlRestore.Action = RestoreActionType.Database;

    string logFile = System.IO.Path.GetDirectoryName(backUpFile);
    logFile = System.IO.Path.Combine(logFile, databaseName + "_Log.ldf");

    string dataFile = System.IO.Path.GetDirectoryName(backUpFile);
    dataFile = System.IO.Path.Combine(dataFile, databaseName + ".mdf");

    Database db = sqlServer.Databases[databaseName];
    RelocateFile rf = new RelocateFile(databaseName, dataFile);
    sqlRestore.RelocateFiles.Add(new RelocateFile(databaseName, dataFile));
    sqlRestore.RelocateFiles.Add(new RelocateFile(databaseName + "_log", logFile));
    sqlRestore.SqlRestore(sqlServer);
    db = sqlServer.Databases[databaseName];
    db.SetOnline();
    sqlServer.Refresh();
}

The issue seems to be that the file names I pick are different from the online DB. I basically want to replace the database on the server with the backup. I get an exception when I call SqlRestore.

The main exception says

{"Restore failed for Server 'localhost'. "}

Digging into the inner exceptions shows these errors

An exception occurred while executing a Transact-SQL statement or batch.

and then

Logical file 'DB' is not part of