添加总计LookupSet值

Question

我正在使用此代码来计算下面列出的各个值：

• 项目A 100
• 项目B 200

• 项目C 300

• 总总计600

  Function SumLookup(ByVal items As Object()) As Decimal
  If items Is Nothing Then
  Return Nothing
  End If
  Dim suma As Decimal = New Decimal()
  Dim ct as Integer = New Integer()
  suma = 0
  ct = 0
  For Each item As Object In items
  suma += Convert.ToDecimal(item)
  ct += 1
  Next
  If (ct = 0) Then return 0 else return suma 
  End Function
  

如何计算GRAND TOTAL值600？