Error when synchronise several combo Boxes

Question

I have a form with subform that we use for Inventory Transaction. The subform has three combo box:

-cboInventoryCategoryID

-cboInventoryGroupID

-cboInventoryID

because we have a wide range of inventory items, for convenience the operator first select the Category, then Group and the last item is Inventory. The first combo and second work good and when you select the first combo box the second filter based the first one, but when I select the third combo an error message appears and say:

"The current field must match the join key '?' in the table that....

I tried to solve the problem by adding this code to second combo box after update event:

DoCmd.RunCommand acCmdSaveRecord

it works but it is not a good solution, because it save the record before entering all items in the row and triggers the Afterupdate event of the subform that make trouble for me.I have some code that don't want to be executed before entering all data in the row.

How can I solve this problem?

Option Compare Database

Private Sub cboInventoryCategoryID_AfterUpdate()
    'Bind the Group name to category Id combobox and filter the Group based on Category
    If IsNull(Me.InventoryCategoryID) Then
        Me.cboInventoryGroupID.RowSource = ""
    Else
        Me.cboInventoryGroupID.RowSource = _
            "SELECT InventoryGroupID,InventoryGroupName " & _
            "FROM tblInventoryGroup " & _
            "WHERE InventoryCategoryID = " & Me.cboInventoryCategoryID & " " & _
            "ORDER BY InventoryGroupName"
       
        Me.cboInventoryGroupID.Requery
            
    End If
            
    
        
End Sub

Private Sub cboInventoryGroupID_AfterUpdate()
    'bind the Inventory name to Inventory group for filtering the list of items
    If IsNull(Me.cboInventoryGroupID) Then
        Me.cboInventoryID.RowSource = ""
    Else
        Me.cboInventoryID.RowSource = "Select InventoryID,InventoryName " _
        & "FROM tblInventory " _
        & "WHERE InventoryGroupID= " & Me.cboInventoryGroupID & " " & _
        "ORDER BY InventoryName"
        
         Me.cboInventoryGroupID.Requery
         Me.cboInventoryID.Requery
    
        'DoCmd.RunCommand acCmdSaveRecord
    End If
End Sub

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Regards,