我的循环体应该插哪里？？

各位VB大佬帮我看看这个怎么修改啊 我实在不知道NEXt k 插哪里了

尽量避免使用goto，k可以在那个位置

Sub WriteFastaK2P()'为计算K2P写Mega计算用文件
    LastRow=Cells(11,10).End(xlDown).Row
    'write batch file
    SavePath$=InputBox("输入文件保存路径?"，"文件保存路径","D:\1Graduate jobs\松鼠科\Mega K2P\")
    If SavePath$="" Then Exit Sub
    SavePath$=SavePath$ & "\": SavePath$=Replace(SavePath$, "\\","\")
    If Not Dir(SavePath$,vbDirectory) = vbNullString Then GoTo 40
    OP=MsgBox("指定的输出文件夹" & SavePath$ & "不存在" & Chr(13) & "是否创建该文件夹并继续运行本程序?",vbExclamation+vbYesNo。"确定")
    If OP = 6 Then MkDir SavePath$ Else Exit Sub
40  For k=1 To LastRow-11+1

        Filename$ = "Group" & Str(k) & ".grp"
        If Filename$ = "" Then Exit Sub
        FullFileName$=SavePath$ & Filename$
        If Dir(FullFileNam,vbDirectory) = vbNullString Then
            GoTo 100
        Else
            OP=MsgBox("指定的文件名已经存在" & Chr(10) & "是否覆盖己存在的文件?",vbExclamation+vbYesNo。"确定")
        EndIf
        If OP = 7 Then
            GoTo 40
        Else
            If OP = 2 Then Exit Sub
        EndIf
100     Open FullFileName$ For Output As 1
        D1$=Cells(k,10)
        a= Split(D1$, "+")
        N1=UBound(a)
        For m = 0 To N1
            Print #1,a(m) &  "=Gp_1"
            D2$= Cells(k,11)
            b=Split(D2$,"+")
            N2=UBound(b)
            For n = 0 To N2
                Print #1,b(n) & "=Gp_2"
            Next n
        Next m
        Close #1
    Next k
    If PNa<0.5 Then OP=MsgBox("分组文件的保存文件夹:" & SavePath$ & Chr(10) & "分组文件的文件名:" & Filename$, vbExclamation,"完成")