主题：[求助]代码求助！！

If e.DataRow("收款总额") IsNot Nothing Then
    Dim Sum1 As Double
    Dim Sum2 As Double
    Dim Sum3 As Double
    Sum1 = DataTables("收款明细表").Compute("Sum(收款总额)", "客户名称='" & e.DataRow("客户名称") & "'")
    Sum2 = DataTables("合同一览表").Compute("Sum(合同总价款)", "客户名称='" & e.DataRow("客户名称") & "'")
    Sum3=DataTables("历史结余明细").Compute("Sum(金额)", " 客户名称= '" & e.DataRow("客户名称") & "'and 年份='" & Date.now.year -1 & "'")
    Dim Sum4 =Sum1-Sum3
    If Sum4< Sum2 Then
        Dim vrs As List(Of DataRow)
        vrs = DataTables("合同一览表").Select("[客户名称]='" & e.DataRow("客户名称") & "'","合同日期 DESC")
        For n As Integer = vrs.Count - 1 To 0
            Dim Sum5 As Double
            Sum5=Sum5 + vrs(n)("合同总价款")
            If Sum5 > Sum4 then

               当前记录和剩下记录的“执行完毕”=否

              elseif Sum5 = Sum4 then

               剩下记录的“执行完毕”=否

            Exit For
            End If
        Next
    ElseIf Sum4= Sum2 Then
        MessageBox.show("该客户货款已全部结清","提示")
    Else
        MessageBox.show("该客户货款已全部结清,并有结余!","提示")
    End If
End If

红色部分也不知道思路对不对，帮忙改正，谢谢！