ObjectDataSource & FormView adding two extra paramaters to Update method giving error non-generic method ...

Hi,
I have a FormView that uses a ObjectDataSource. It retreives data alright
but when updating it gives a

ObjectDataSource 'ObjectDataSourceCatalogueItem' could not find a
non-generic method 'UpdateByCatalogueItemID' that has parameters:
CatalogueItemTitle, CatalogueItemDescription, CatalogueItemImage,
Original_CatalogueItemID, CatalogueItemID, CatalogueItemREFItemNumber,
original_CatalogueItemREFItemNumber.

where as the actual UpdateParameters looks like

<UpdateParameters>
<asp:Parameter Name="CatalogueItemTitle" Type="String" />
<asp:Parameter Name="CatalogueItemDescription" Type="String"
/>
<asp:Parameter Name="CatalogueItemImage" Type="String" />
<asp:Parameter Name="CatalogueItemREFItemNumber"
Type="String" />
<asp:Parameter Name="Original_CatalogueItemID" Type="Int32"
/>
</UpdateParameters>

Why is it adding "
, CatalogueItemID, CatalogueItemREFItemNumber,
original_CatalogueItemREFItemNumber.
"

onto the update parameter list? How can I remove them?

Thanks in advance.