问题：将“学生信息表”字段信息写入到“学年收费名单”相应字段，在写入之前判断“学年收费名单”是否存在已有记录（判断条件为“考生号”、“学年”相同），如果存在记录则覆盖写入，如果不存在相同记录，重新建一行再写入。以下为代码，提示“未将对象引用设置到对象的实例”错误。谢谢。

Dim Cols1() As String = {"考生号","学号","姓名","专业","年级","班级","性别","身份证","籍贯","联系电话","入学时间","注册情况","是否毕业","备注"}

Dim Cols2() As String = {"考生号","学号","姓名","专业","年级","班级","性别","身份证","籍贯","联系电话","入学时间","注册情况","是否毕业","备注"}

Dim t As Table = Tables("学年收费名单")

Dim newcount As Integer = 0

Dim oldcount As Integer = 0

For Each dr1 As DataRow In DataTables("学生信息表").DataRows

If dr1("是否毕业")="否" And dr1("注册情况")="是" Then

Dim r As DataRow = t.DataTable.Find("学号= '" & dr1("考生号")& "' And 学年= '" & Tables("基本设置").Text(0,0) & "'")

If r Is Nothing Then

For i As Integer = 0 To Cols1.Length -1

r(Cols2(i)) = dr1(Cols1(i))

r("添加时间")=Today.Date()

oldcount += 1

Else

Dim dr2 As DataRow = DataTables("学年收费名单").AddNew()

For i As Integer = 0 To Cols1.Length -1

dr2(Cols2(i)) = dr1(Cols1(i))

dr2("添加时间")=Today.Date()

newcount += 1

End If

MsgBox("已成功生成缴费名单,新增" & newcount & " " & "更新旧数据" & oldcount)

主题：未将对象引用设置到对象的实例

未将对象引用设置到对象的实例