PHP CLasses and DB Access

Hello All, I am new to working with classes and have created to classes. I have a session class which writes the sessions to a table and I have a login class which is used to determine if you can login or not or if a session currently exists. The issue I am running into is that I would like to use a dbconnect.php include in both classes to minimize administration. Unfortunately I cannot seem to get the include to work and I am wondering where to go from here. If any one has any suggestions I would be very appreciative. Thanks for the help, Jason