Relationships... Driving Me Crazy!

Hehe... and since me and my girlfriend just broke up, that seems applicaple both in the dbase and the real world ;)

I have one Access Database. For now containing three Tables:

KlantNAW (customer adress data) with one primary key, Klantnummer (clientnumber) which is an Autonumber Data Type, Long Int, Increment, Indexed: Yes (No dupes).

CaseDateTimeInfoTable with one primary key, Casenumber which is an Autonumber type, Long Int, Incremental, Indexed: Yes (No dupes).
Within this table I have included the Klantnummer field from KlantNAW as a Number, Indexed: Yes (dupes OK).

CaseTechInfoTable with no primary keys but with both the KlantNummer field and the CaseNumber field included. Both have a direct relationship to the tables in which those two values are created. Both values are now of type Number, both are Indexed, but Klantnummer is set to Duplicates OK and Casenumber is set to No Duplicates. I don't know if it might be wiser to just not index those values in this table, since they are already indexed in the tables in which they are created, if someone could tell me which is better in this case, please do.

I have created a one-to-many relationship (well actually, access seems to decide whether it becomes a one-to-many or one-to-one relationship) between KlantNAW.Klantnummer and CaseDateTimeInfoTable.Klantnummer with Join Type 1 and I've created a Join Type 1, one-to-many relationship between KlantNAW.Klantnummer and CaseTechInfoTable.Klantnummer.
There is only one extra relationship left, which is a one-to-one, Join Type 1 CaseDateTimeInfoTable.CaseNumber with CaseTechInfoTable.CaseNumber.

So ehrm.... a recap:
KlantNAW.Klantnummer (P-key) with CaseDateTimeInfoTable.Klantnummer
KlantNAW.Klantnummer (P-key) with CaseTechInfoTable.Klantnummer
CaseDateTimeInfoTable.CaseNumber (P-key) with CaseTechInfoTable.Casenumber

If I leave it like that the dbase works perfectly except for the fact that when I delete a customer the related case date/time info and the case tech info don't delete with the client account accordingly.

So, I thought I'd "Enforce Referential Integrity" and "Cascade Delete Related Records". I do not know if it would be wise to also enable "Cascade Update Related Fields". Could someone please tell me if that would be wise to do or not? And maybe even why... I have some beginner and more advanced books but can't be sure, probably because of lack of experience (or maybe lack of brains ;) ).

Anyway, back to the problem: when I make all the relationships to Enforce Rererential Integrity and I add a customer through a form (KlantNAW_InvoerForm) and click the "Create new case for this customer" button, the form I use for entering the case date info pops up nicely, but when I try to close that form I get an Error stating: "You cannot add or change a record because a related record is required in table "KlantNAW"". So, I click ok, then get a messagebox stating I can't save the record at this time. Do I want to close anyway? .... well, ok. Let's do that. And now the strange thing is that after that, when I do absolutely nothing other than pressing the create new case button again, enter the date/time info into the form and close it again, no errors or messages come up. Wel... that should happen the first time around right? What's wrong?

Now... I'm really lost. I'm new at this. I made some tables, queries and forms, set all options for all values, that which I didn't understand mostly tried solving or finding out on my own but now I'm hitting a brick wall.

If you guys and gals could help me out I would really be very grateful for that.

EDIT: I even tried making it more simple by removing all relationships and creating just one new one between KlantNAW.KlantNummer and CaseDateTimeInfoTable.Klantnummer (type 1, enforce referential integrity and cascade deleted records) but still, the same problem arises.

EDIT2: made sure it was not a form thing by just putting in data in the table data views directly. Same thing occurs.