Ceystal Report Problem

Hi,

My problem is quite strange. Below, I have explained it.

I have following tables in my project:
1) PurchaseParent
2) PurchaseChild
3) Item.

PurchaseParent has following fields:
- PurchaseParentId --P.K.
- BillNo
- BillDate

PurchaseChild has following fields:
- PurhcaseChildId --P.K.
- PurchaseParentId --F.K.
- ItemId --F.K.
- Quantity
- BatchNo

Item has following fields:
- ItemId --P.K.
- ItemName

Now I am generating one report. I have designed form, which has 2 controls:
- ComboBox which is being filled with 12 months.
- Command Button (Report)

Now when I select any Month from combobox say, January then list of items should come whose bill was made in the Month of January. I am getting all item names correctly. Now my problem is that how should i send all records to crystal report?

Kindly help me.