这是我做的最终代码。没有错误，但是有几行代码测试，没有看到行颜色的改变。

求高手帮忙分析！

Dim d1 As Date = e.Row("计划竣工")
Dim d2 As Date = Date.today
Dim d3 As Date = e.Row("竣工日期")
Dim t As TimeSpan = d1-d2
Dim d As timespan = d3-d1
If e.Row.IsNull("计划竣工") = False \'计划竣工不为空
    If e.Row.isnull("竣工日期") \'竣工日期为空
        Select Case t.days
        Case 0 To 10
        e.style = "即将到期"
        Case -10 To -1
        e.style = "拖期十天以内"
        Case -11 To -20
        e.style = "拖期十到二十天"     （不知道为啥只有这一段没有显示出预计效果）
        Case -21 To -1000
        e.style = "严重拖期"
        End Select
    Else If e.Row.isnull("计划竣工") = False
        Select Case d.days
        Case 1 To 10
        e.style = "拖期十天以内"
        Case 10 To 20
        e.style = "拖期十到二十天"
        Case 20 To 1000
        e.style = "严重拖期"
        End Select
     End If
End  If

http://www.foxtable.com/help/topics/0656.htm

整行不是更简单吗，看这个事件的示例二

不好意思。。没仔细看，劳烦了！

感谢！另外再劳烦问下，我现在适用的软件会不会做出项目以后过一段时间会过期？

这样试试:

 Dim d1 As Date = e.Row("计划竣工")
Dim d2 As Date = Date.today
Dim t As Integer = DateDiff("d",d1,d2)
If t < 10 Then
    e.Style = "即将到期"
End If

我完整的代码是这么做的，麻烦你看看，指导指导。

现在提示错误。 编码错误：“Is”要求具体引用类型的操作数，但此操作数的值类型为“date".   错误代码：If d3 is nothing=true

Dim d1 As Date = e.Row("计划竣工")
Dim d2 As Date = Date.today
Dim d3 As Date = e.Row("竣工日期")
Dim t As TimeSpan = d1-d2
Dim d As timespan = d3-d1
If d3 Is Nothing = True
    If t.days < 10 Then
    e.Style = "即将到期"
    End If
Else
    Select d.days
    0 < Case < 10
    e.style = "即将到期"
    Select d.days
    10 <= Case <= 20
    e.style = "拖期十到二十天"
    Case > 20
    e.style = "严重拖期"
End If

这样试试?

Dim d1 As Date = e.Row("计划竣工")
Dim d2 As Date = Date.today
Dim d3 As Date = e.Row("竣工日期")
Dim t As TimeSpan = d1-d2
Dim d As timespan = d3-d1
If d3 Is Nothing Then
    If t.Totaldays < 10 Then
        e.Style = "即将到期"
    End If
Else
    If d.Totaldays >=0 Or d.Totaldays<= 10 Then
        e.style = "即将到期"
    ElseIf d.Totaldays >=10 Or d.Totaldays<= 20 Then
        e.style = "拖期十到二十天"
    ElseIf d.Totaldays >= 20 Then
        e.style = "严重拖期"
    End If
End If

还是一样的错误提示啊....怎么回事？