Access Control on subform / combo box requesting parameter

[Barrie Brown]

I am a Newbie in Access and have the following in my database
Tables:
tblProducts
tblCategory
Forms:
frmQuote
SubForm:
frmQuoteDetails which contains two combo boxes,
CategoryID with Control Source = CategoryID, Row Source = SELECT [tblCategory].[CategoryID], [tblCategory].[Category] FROM [tblCategory] ORDER BY [Category]
Additionally on the CategoryID combo box is this AfterUpdate event procedure:

Private Sub CategoryID_AfterUpdate()
Me.ProductID.RowSource = " SELECT ProductName From tblProducts WHERE CategoryID = " & " Me.CategoryID "
Me.ProductID = Me.ProductID.ItemData(0)
End Sub

ProductID with Control Source and Row Source both empty, and Row Source Type as Table/Query.

On running the After Update procedure I get "Enter Parameter Value for Me.CategoryID

I would appreciate any assistance