Tried this in as connection string
connectionString=\"Server=.\\SQLEXPRESS; AttachDbFilename=E:\\Database\\dnn49.mdf;Database=dnn49; Trusted_Connect
i can't say whether you people got the solution for the problem or not, but i suggest a simple one here...
copy the mdf and ldf file to your SQLServer installation directory, you may place it in backup folder of the directory. then try it
i had used it many times...
Good Luck