SQL Server 2008 R2 on Server 2012 R2 web site connection issue - sql-server-2008-r2

Question

I have been using this connection string with no problem on a number of databases and MS operating systems. Windows Server 2003, 2008 R2 and 2012 R2 Eval, all Express versions.
I am now trying to deploy to a new Windows Server 2012 R2 installation and I am getting some errors. I have the SQL Server 2008 R2 installation on the Windows Server 2012 R2 machine.
My con string:
connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\myDB.mdf;Integrated Security=True;User Instance=False" ProviderName="System.Data.SqlClient"
I think this must have something to do with the installation sequence of the components on the new server.
I have in the past been able to simply copy myDB.mdf to basically any web server and open or access the DB tables. This DB includes an ASP membership for the web site that it is tied to.
Here is the error:
CREATE DATABASE permission denied in database 'master'. An attempt to
attach an auto-named database for file
C:\inetpub\techTran\App_Data\myDB.mdf failed. A database with
the same name exists, or specified file cannot be opened, or it is
located on UNC share.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Data.SqlClient.SqlException: CREATE
DATABASE permission denied in database 'master'.
I thought I understood what this error was. I have checked permissions and they match the other servers where this database has been deployed. My SQL Server installations are basically all the same. The only difference here is that this is Windows Server 2012 R2 on a VM. Or I did not install the SQL Server 2008 R2 the same way I have done in the past 5 servers I have set up. (Which I am guessing is probably the case.)
UPDATE: Uninstalled and reinstalled SQL Server and SSMS.
I know there is only one database name on the server called myDB.mdf, so I don't believe the "same name" portion of error. I have added security to the db so that it can be opened and I even installed Visual Studio 2012 on the server to be certain that the db could be opened. I can run the full app on the localhost (server 2012) but I can not access it over a web connection.
I believe the specific error message relating to
CREATE DATABASE permission denied in database 'master'
is the issue.
I have never seen this error before.
I typically assign NETWORK SERVICE account to the database to allow access and this is how this one is set up as well. I also thought this might be a connection string issue. But this same string has worked on 4 different servers now with no changes. Server 2003, 2008 R2, and 2012 (demo platform)(all Express versions), now in production this is failing.
The home page loads and then the login throws the above error.

Answer 1

Your connection string says AttachDbFilename=|DataDirectory|\myDB.mdf. Well, your path must have changed in one place (SQL Server) and not the other (app configuration). AttachDbFilename will try to create a new DB if it can't find that file. That's probably your error.
As an aside, Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, and Windows Server 2012 R2 all have differences, especially with security and in particular with how SQL Server behaves, but you keep using them interchangeably. That makes it very confusing to tell what's going on. Also, your connection string says Data Source=.\SQLEXPRESS. Is this SQL Server Express? Because that has important differences with most other editions of SQL Server, too. More recent editions are very similar to Standard edition, but the older the edition, the more quirks it has. They're generally considered different beasts.

Answer 2

SOLVED: I am not sure how this happened or perhaps why it didn't happen. But for some reason the installation of SQL did not add the NETWORK SERVICE account to the sysadmin Server Role. I cross referenced this with the SERVER 2003 installation where SQL 2008 R2 is also running, and discovered that the sysadmin SQL Server Role included NETWORK SERVICE in my correctly functioning environment. So once I added the user account to this role, everything came up fine.
I believe this might have been an issue during the installation of SQL 2008 R2. I did specify NETWORK SERVICE, but for some reason it was not provided the role.