Cannot connect to SQL 2008 R2 from MS Access 2010

I'm trying to connect to a SQL Server from a client machine running Access 2010. Here is what I've done so far: Open Access; New .adp project (so I can manipulate tables through Access); it asks if I want to connect to a server, click yes; "1. Select or enter a server name." I select the name of my server from the dropdown list (the server instance is not shown here, just the server name, ie SERVER instead of SERVER\SQLEXPRESS); "2. Enter information to log on to the server:" at this point I can select either Windows authentication or SQL but either way returns the same result; "3. Select the database on the server:" when I click the dropdown arrow to make the selection I get these two errors: "[DBNETLIB][ConnectionOpen(Invalid Instance()).]Invalid connection." "Login Failed. Catalog information cannot be retrieved.". I've also tried to type in the instance name (SERVER\SQLEXPRESS) in box 1 but I still get the er ...