Need Help Urgently!!!

Hey guys. I'm an A level ICT student (british exam) and I am currently working on a patient management database in Access as a project for the A2. So far all has been going well. The problem lies within one of my forms. The form (called frmTreatment) is a form with a subform. The main form contains patient and treatment data, whilst the subform allows for costs to be added to the system. The problem is that when making a combo box to select a patient by the option "Find a record on...combo box", the combo box does absolutely nothing. It brings up an empty list, whereas it should bring up Patient ID, Patient Name and Patient Surname. I suspect its a problem with the relationships. What the combo box should do is bring up patients from tblPatients and subsequently present data on them in the rest of the form's fields.

The second problem is with the subform. I want to add a combo box that allows the user to select the cost from the tblCosts, much in the same way with the afforementioned Patients combo box. Yet subforms won't allow new objects to be added and I can't see any way of making Cost ID perform such a function.

Can someone please help me by having a look at my project, and in particular the frmTreatment? I can't seem to pinpoint the error out and everything seems fine. I've done normalisation and everything already. The project is due after the Xmas holidays, plus its difficult to get in touch with my ICT instructor now. So any help will be appreciated.


Thanks in advance,
Elh

PS: If you're willing to help give me your e-mail so I can send a zipped version of the project to you in order for you to help.