Form design error- can't find record.

[SillySally]

Hi. I am struggling with my form design. I am violating
the one-to-many rule and keep getting errors that Access
can't find the key.

Here's my table design:

Contacts
ContactID
MemberCategoryID
LastName...

MemberCategory
MemberCategoryID
MemberCategory
CategoryDues

DuesHeader
DuesID
ContactID
DateDue

DuesLineItem
DuesItemID
DuesID
DuesItemTypeID
AmountDue
DateCreated

DuesItemType
DuesItemTypeID
DuesItemType

And then there are the corresponding Payment tables
(Header, LineItem, Types)

Contacts have an associated MemberCategory, which drives
the cost of Dues. The CategoryDues correctly populates
AmountDue (thanks to Ken). But I haven't set my form up
correctly.

I'd like the form to be a datasheet view to show annual
Dues. I want DateCreated, AmountDue, DueDate, and a
combo box to select the DuesType. My record source seems
to have problems with the DueDate and the combo box for
the DuesType. Can information from these tables show up
on one datasheet form, or do I need a form/subform
setup? Could you suggest a record source that will work
for the datasheet (I hope) or form/subform? Thanks for
your time!