"Recordset not Updateable - Need to set Unique Table"

[xlatb]

I keep getting this message when joining 3 tables.
I have customers, postalnumbers and customertypes.

Customers.Postalnr relates to Postal.Postalnr(int(key)) where i need to find Postal.AreaName (WHERE Customers.Postalnr = Postal.Postalnr)

Customers.CustomerType relates to CustomerTypes.CustomerType (int(key)) where a simple description Customer.Description (nvarchar(255)).

The problem occurss when i try to make a form out of the Customers table. Access 2000 (From Office 2k pro) and MS SQL7.0 used.

All attempts at making a form either returns a blank form when using autoform or hands back "Recordset not updateable (writeprotected) you need to set Unique Table property"

No where can i find this property, do i need to alter Access' own generated SQL statements to make it work?

I'm not totally lost at SQL, as i've used MySQL with PHP for a while. No books i've read have ever mentioned this problem, and it happens on everyone elses computer too.

I would be thankfull if someone could help me out with this one, it has driven me mad for weeks(!)