以下代码是一个打印表格的代码，一套房子打一张表，黄色部分希望实现该表的行数如果超过20行就强制换行，怎么修改？

Dim dt1 As Table=Tables("楼面规划_table1")
Dim dt2 As DataTable=DataTables("楼面台账账面")
Dim doc As New PrintDoc \'定义一个报表
Dim rt As New prt.RenderTable() \'定义一个表格对象
Dim rs As New prt.RenderText() \'定义一个文本对象
For i As Integer = dt1.TopRow To dt1.BottomRow
    \'Dim doc As New PrintDoc \'定义一个报表
    \'Dim rm As prt.RenderEmpty
   
    rt = New prt.RenderTable() \'定义一个表格对象
    rs = New prt.RenderText() \'定义一个文本对象
    rs.Text =  DataTables("基本情况").find("项目= \'单位名称\'")("内容") & "楼面情况" \'设置文本对象的内容
    rs.Style.Font = New Font("黑体", 16 , FontStyle.Bold) \'设置文本对象的字体
    rs.Style.TextAlignHorz = prt.AlignHorzEnum.Center \'文本内容水平居中
    rs.Style.Spacing.Bottom = 2
    Doc.PageSetting.LeftMargin = 20 \'设置左边距
    Doc.PageSetting.RightMargin = 10 \'设置右边距
    Doc.PageSetting.TopMargin = 20 \'设置上边距
    Doc.PageSetting.BottomMargin = 20 \'设置下边距
   
    rt.Width = "Auto" \'表格宽度为自动,也就是等于各列设置宽度之和
    rt.Style.TextAlignHorz = prt.AlignHorzEnum.Center \'水平居中
    rt.Style.TextAlignVert = prt.AlignVertEnum.Center \'垂直居中
    doc.Body.Children.Add(rs) \'将文本对象加入到表格中
    doc.Body.Children.Add(rt) \'将表格对象加入到报表中
    rt.Style.GridLines.All = New prt.LineDef \'将网格线类型设为默认类型
    \'For d As Integer = 0 To 3
    \'rt.cells(0,d).Style.GridLines.top = New prt.LineDef(0,Color.Green)
    \'rt.cells(0,d).Style.GridLines.left = New prt.LineDef(0,Color.Green)
    \'rt.cells(0,d).Style.GridLines.right = New prt.LineDef(0,Color.Green)
    \'Next
    \'For f As Integer = 0 To 20
    \'rt.cells(f,11).Style.GridLines.top = New prt.LineDef(0,Color.Green)
    \'rt.cells(f,11).Style.GridLines.bottom = New prt.LineDef(0,Color.Green)
    \'
    \'Next
    rt.Width = 248 \'表宽为150毫米
    rt.Height = 170  \'表高为150毫米
    \'rt.Cols(4).Width = 20
    \'rt.Cols(11).Width = 2
    Dim BaRow As DataRow
    BaRow =DataTables("备案登记").find("楼房编号= \'" & Tables("楼面规划_table1").Rows(i)("楼房编号") & "\'")
    Dim DjRow As DataRow
    DjRow =DataTables("登记购房明细").find("楼房编号= \'" & Tables("楼面规划_table1").Rows(i)("楼房编号") & "\'")
    Dim ZmHzs As List(Of String)
    ZmHzs =DataTables("楼面台账账面").SQLGetValues("购买户主","楼房编号= \'" & Tables("楼面规划_table1").Rows(i)("楼房编号") & "\'")
   
    Dim SjRows As List(Of DataRow)
    SjRows =DataTables("楼面台账收款").SQLSelect("楼房编号= \'" & Tables("楼面规划_table1").Rows(i)("楼房编号") & "\'")
    rt.Cells(0,1).SpanCols = 3 \'第5行第2个单元格向右合并3列
    rt.Cells(2,5).SpanCols = 3 \'第5行第2个单元格向右合并3列
    \'rt.Cells(1,0).SpanRows = 3 \'第1行第5个单元格向下合并6行
   
    rt.Cells(0,0).Text = "楼房位置"
    rt.Cells(0,1).Text = dt1.Rows(i)("楼房编号")
    rt.Cells(0,4).Text = "备案编号"
    rt.Cells(0,6).Text = "备案户名"
    rt.Cells(1,0).Text = "备案日期"
    rt.Cells(1,2).Text = "面        积"
    rt.Cells(1,4).Text = "单        价"
    rt.Cells(1,6).Text = "金        额"
    rt.Cells(2,0).Text = "联系电话"
    rt.Cells(2,2).Text = "身份证号"
    rt.Cells(2,4).Text = "户籍地址"
    If BaRow IsNot Nothing Then
        rt.Cells(0,5).Text = BaRow("备案编号")
        rt.Cells(0,7).Text = BaRow("购买户主")
        rt.Cells(1,1).Text = BaRow("备案日期")
        rt.Cells(1,3).Text = BaRow("面积")
        rt.Cells(1,5).Text = BaRow("单价")
        rt.Cells(1,7).Text = BaRow("金额")
        rt.Cells(2,1).Text = BaRow("联系电话")
        rt.Cells(2,3).Text = BaRow("身份证号")
        rt.Cells(2,5).Text = BaRow("户籍地址")
    End If
   
    Dim m As Integer = 0
    For r As Integer = 0 To ZmHzs.Count - 1
        Dim Rows As List(Of DataRow)
        Rows =DataTables("楼面台账收款").SQLSelect("楼房编号= \'" & Tables("楼面规划_table1").Rows(i)("楼房编号") & "\' and 购买户主 = \'" & ZmHzs(r) & "\'")
        rt.Cells(2 + 1 + m,0).SpanCols = 2 \'第5行第2个单元格向右合并3列
        rt.Cells(2 + 1 + m,0).Text = "第" & r + 1 & "户   户名:" & ZmHzs(r) & "  收据金额   " & Format(DataTables("楼面台账收款").SQLCompute("sum(收款金额)","楼房编号= \'" & Tables("楼面规划_table1").Rows(i)("楼房编号") & "\' and 购买户主 = \'" & ZmHzs(r) & "\'"),"#,###.00")
        rt.RowGroups(2 + 1 + m,1).Style.BackColor = Color.LightGray
        rt.rows(2 + 1 + m).Style.Font = New Font("黑体", 10 , FontStyle.Bold)
        rt.Cells(2 + 1 + m,2).Text = "联系电话"
        rt.Cells(2 + 1 + m,4).Text = "身份证号"
        rt.Cells(2 + 1 + m,6).Text = "户籍地址"
        rt.Cells(2 + 2 + m,0).Text = "付款账户"
        rt.Cells(2 + 2 + m,1).Text = "付款账号"
        rt.Cells(2 + 2 + m,2).Text = "金额"
        rt.Cells(2 + 2 + m,3).Text = "收款账户"
        rt.Cells(2 + 2 + m,4).Text = "收款账号"
        rt.Cells(2 + 2 + m,5).Text = "收款日期"
        rt.Cells(2 + 2 + m,6).Text = "核查情况"
        rt.Cells(2 + 2 + m,7).Text = "待查原因"
        If DjRow IsNot Nothing Then
            rt.Cells(2 + 1 + m,3).Text = BaRow("联系电话")
            rt.Cells(2 + 1 + m,5).Text = BaRow("身份证号")
            rt.Cells(2 + 1 + m,7).Text = BaRow("户籍地址")
        End If
        \'msgbox(Rows.Count - 1)
        For n As Integer = 0 To Rows.Count - 1
           
            rt.Cells(2 + 3 + m + n ,0).Text = Rows(n)("付款情况_付款户名")
            rt.Cells(2 + 3 + m + n ,1).Text = Rows(n)("付款情况_付款账号")
            rt.Cells(2 + 3 + m + n ,2).Text = Format(Rows(n)("收款金额"),"#,###.00")
            rt.Cells(2 + 3 + m + n ,2).Style.TextAlignHorz = prt.AlignHorzEnum.right
            rt.Cells(2 + 3 + m + n ,3).Text = Rows(n)("收款情况_收款户名")
            rt.Cells(2 + 3 + m + n ,4).Text = Rows(n)("收款情况_收款账号")
            rt.Cells(2 + 3 + m + n ,5).Text = Rows(n)("收款情况_收款日期")
            rt.Cells(2 + 3 + m + n ,6).Text = Rows(n)("核查情况")
            rt.Cells(2 + 3 + m + n ,7).Text = Rows(n)("待查原因")
            rt.Cells(2 + 2 + m ,2).Style.TextAlignHorz = prt.AlignHorzEnum.Center
        Next
        m = m + Rows.Count + 2
        \'If m > 18
        \'rm.BreakBefore = prt.BreakEnum.Page
        \'End If
        \'doc.Body.Children.Add(rm)
        \'msgbox(m)
    Next
    msgbox(m)
Next
doc.PageSetting.Landscape = True \'横向打印
Doc.Preview() \'预览报表

不能像你这样处理。必须一页一个table，才行，参考

http://www.foxtable.com/webhelp/scr/2241.htm