Problems with TransactionScope in ASP.NET

I've build a class to synchronize data between two different datasources. This synchronization is divided into multiple parts (and methods). Every method has his own TransactionScope and the methods are run sequentially.

Everytime I Run this code I get the following errormessage:

"The transaction associated with the current connection has completed but has not been disposed. The transaction must be disposed before the connection can be used to execute SQL statements."

The following code is an example of such a method with a TransactionScope:

private void SomeMethod()
{
        try
        {
            using (var _transactionScope = new TransactionScope(TransactionScopeOption.Required, transactionOptions))
            {
                using (SqlConnection _connection = new SqlConnection(connectionstring))
                {
                    _connection.Open();

                    DoSomething()...
                }

                _transactionScope.Complete();
            }
        }
        catch (TransactionAbortedException e)
        {
            nlog.Error(string.Format("The transaction has been aborted: {0}", e.Message));
            throw e;
        }
        catch (Exception e)
        {
            throw e;
        }
}

It seems that the call "_transactionScope.Complete()" isn't enough to kill the transactionscope.. Does anyone have a clue what i'm doing wrong?

Thanks in advance!

UPDATE Спасибо за ответы. После нескольких тестов я обнаружил, что эта проблема существует только тогда, когда есть несколько запросов в одном методе. например:

 try
    {
        using (TransactionScope _transactionScope = new TransactionScope(TransactionScopeOption.Required, transactionOptions))
        {
            using (SqlConnection _connection = new SqlConnection(connectionstring))
            {
                _connection.Open();

                //new method:
                using (TransactionScope _transactionScope = new TransactionScope(TransactionScopeOption.Suppress))
                {
                    //a selectquery
                }

                //an update or insert query

            _transactionScope.Complete();
        }
    }