Curso Budget Control

Olá... Estou iniciando em .Net. Estou estudando o curso do Welliton Flor. Desenvolvimento de controle orçamentário doméstico. Estou na parte IX do curso. Quando ele cria o webService para testar as classes. Segui passo a passo. O problema está na conexão. Não cadastra. Emite a seguinte mensagem:

System.Data.SqlClient.SqlException: Cannot open database "Budget" requested by the login. The login failed.
Login failed for user 'DMS-09F59DBA1E2\Daiana Mowry'.
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
at System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK)
at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject)
at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart)
at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance)
at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance)
at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection)
at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options)
at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject)
at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject)
at System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject)
at System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
at System.Data.SqlClient.SqlConnection.Open()
at Microsoft.Practices.EnterpriseLibrary.Data.Database.OpenConnection()
at Microsoft.Practices.EnterpriseLibrary.Data.Database.ExecuteNonQuery(DbCommand command)
at Microsoft.Practices.EnterpriseLibrary.Data.Database.ExecuteNonQuery(CommandType commandType, String commandText)
at BudgetBusiness.Cards.AddCard() in C:\Documents and Settings\Daiana Mowry\Meus documentos\Visual Studio 2005\Projects\Budget\BudgetBusiness\Cards.cs:line 41
at Cards.AddCard(String CardDesc, DateTime CardLastInvoice, String CardFlag)
Acho que é no Sql Server 2005. Na configuração. Quando o instalei, ele criou automaticamente um servidor. Estou tentando acessá-lo. Mas exibe o erro acima. Onde está o meu erro? Criei um Dataset no Server Explorer. E apontei para o servidor e o nome do banco. Testei a conexão e foi bem sucedida. Mesmo assim dá erro. Quem puder ajudar, por favor, ficarei grata.
Meu MSN é: daianamowry@hotmail.com.

Obrigada a todos.
Boa noite.