bbcompent1

Try to make sure that your filename for the database is correct and you're using the correct path. Like this:

string connectString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=db.accdb;Persist Security Info=True;"; if its in the root,

in the data directory:

string connectString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|db.accdb;Persist Security Info=True;";

My addition——

For accdb database，I think it's better to use ACE driver instead of Oledb4.0。For connection string，you can find more at：

http://www.connectionstrings.com/access-2007