Have you enabled remote connections? Yes, you have to explicitly enable it
to accept connections from external machines. Doesn't matter what libraries
or connection strings you are sending. If remote connections are not
enabled, the only thing that any SQL Server 2005 database will respond to is
something from the machine it resides on.
Disclaimer: This communication is an original work and represents my sole
views on the subject. It does not represent the views of any other person
or entity either by inference or direct reference.