Auto Increment Not Working - SQL Identity field

Question

I am new to Visual Basic & SQL server but have some experience in Access & VBA. But this is a steep learning curve!
I am banging my head against a wall with a problem..
All of my tables in this database are in the dataset. The main one being tblItems with a PK 'ITEMID'
I have 2 forms - the first one is used to lookup an item the second displays the item's full details.
On the first form (lookup) I have a 'Add New' button which launches the second form with the code - frmProductDetail.VItemsBindingSource.AddNew()
This opens the form with empty boxes as expected. I have a 'Save' button on the second form with the following code -
        Dim row As SASHItemsDataSet.tblItemsRow
        row = SASHItemsDataSet.tblItems.NewRow
        With row
            .ITEMCODE = txtItemCode.Text
            .ITEMDESCRIPTION = txtItemDescription.Text
            .CATEGORY = cmbItemCategory.SelectedValue
            .PURCHCOST = txtPurchCost.Text
            .SELLCOST = txtSellPrice.Text
            .UNIT = cmbUOM.SelectedValue
            .VATID = cmbVAT.SelectedValue
            .WHLOCATION = cmbWHLoc.SelectedValue
        End With
        SASHItemsDataSet.tblItems.Rows.Add()
        Try
            Me.Validate()
            Me.VItemsBindingSource.EndEdit()
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Critical + MsgBoxStyle.OkOnly, "UPDATE FAILED")
        End Try
My problem is I get the error msg box with the following error 'Column 'ITEMID' does not allow nulls'
This field is set as a auto incrementing identity field with all the correct settings shown in Visual Studio so it shouldn't be coming back as null.
I have Googled for hours & tried all sorts with no luck..
I have clearly gone wrong somewhere but I can't work out where... any help appreciated!
James

Answer 1

This is the code on frmProductLookup that opens the form...
        frmProductDetail.Show()
        frmProductDetail.VItemsBindingSource.AddNew()
This is the code on frmProductDetail_Load...
        'TODO: This line of code loads data into the 'SASHItemsDataSet.tblVAT' table. You can move, or remove it, as needed.
        Me.TblVATTableAdapter.Fill(Me.SASHItemsDataSet.tblVAT)
        'TODO: This line of code loads data into the 'SASHItemsDataSet.tblWarehouseLocations' table. You can move, or remove it, as needed.
        Me.TblWarehouseLocationsTableAdapter.Fill(Me.SASHItemsDataSet.tblWarehouseLocations)
        'TODO: This line of code loads data into the 'SASHItemsDataSet.tblStockUnits' table. You can move, or remove it, as needed.
        Me.TblStockUnitsTableAdapter.Fill(Me.SASHItemsDataSet.tblStockUnits)
        'TODO: This line of code loads data into the 'SASHItemsDataSet.tblItemCategory' table. You can move, or remove it, as needed.
        Me.TblItemCategoryTableAdapter.Fill(Me.SASHItemsDataSet.tblItemCategory)
        'TODO: This line of code loads data into the 'SASHItemsDataSet.vItems' table. You can move, or remove it, as needed.
        'Me.VItemsTableAdapter.Fill(Me.SASHItemsDataSet.vItems)
        Me.VItemsTableAdapter.Fill(Me.SASHItemsDataSet.vItems)
        Me.VItemsBindingSource.Position = Me.VItemsBindingSource.Find("ITEMID", _passedText)
        Me.txtWKSName.Text = Environment.MachineName
        Me.txtSellPrice.Text = FormatCurrency(Me.txtSellPrice.Text)
        Me.txtPurchCost.Text = FormatCurrency(Me.txtPurchCost.Text)
        Me.txtPriceIVAT.Text = FormatCurrency(Me.txtSellPrice.Text + (Me.txtSellPrice.Text * 0.2))
On the tblItemTableAdapter this is the Command Text for the Insert Command...
INSERT INTO tblItems
                         (ITEMCODE, ITEMDESCRIPTION, UNIT, WHLOCATION, VATID, PREFSUPPLIER, CATEGORY, PURCHCOST, SELLCOST, INACTIVE)
VALUES        (@ITEMCODE,@ITEMDESCRIPTION,@UNIT,@WHLOCATION,@VATID,@PREFSUPPLIER,@CATEGORY,@PURCHCOST,@SELLCOST,@INACTIVE)
SQL Server Management Studio clearly shows the column as an Identity column. If I add a row through SSMS it does create an PK identity automatically. I have also dropped the ITEMID column & recreated through SSMS which has no effect.
I am now considering creating a separate form just for adding an item but I have managed it in Access but am just struggling with VB!
Thanks,
James