mapgis二次开发添加字段VB.NET

<P>使用VB.net(2005)进行Mapgis二次开发，如何添加属性字段（以下是 VB 的代码，但是在VB.net中不可以运行），恳请哪位仁兄出手相助：</P>
<P>'添加字段<BR>Private Sub APPENDFLD_Click()<BR>Dim pntObj As PntArea<BR>Dim linObj As LinArea<BR>Dim regObj As RegArea<BR>Dim fldinf As Field_Head<BR>Dim mystru As Record_Head<BR>Dim flag As Boolean</P>
<P>Set pntObj = New PntArea<BR>If (pntObj.Load()) Then</P>
<P>'构造需添加的字段信息<BR>    Set fldinf = New Field_Head<BR>    fldinf.fieldname = "newflddouble"<BR>    fldinf.fieldtype = gisDOUBLE_TYPE<BR>    fldinf.point_leng = 0.3<BR>    fldinf.msk_leng = 10<BR>    fldinf.edit_enable = 1<BR>    fldinf.ptc_pos = -1<BR>'方法1 ...添加字段<BR>    flag = pntObj.ATT.stru.AppendField(fldinf)<BR>'    fldinf.fieldname = "newfldstr"<BR>'    fldinf.fieldtype = gisSTR_TYPE<BR>'    fldinf.msk_leng = 32<BR>'    fldinf.edit_enable = 1<BR>'    fldinf.ptc_pos = -1<BR>'    flag = pntObj.Att.stru.AppendField(fldinf)<BR>'方法2：...添加字段<BR>'    Set mystru = pntObj.Att.stru.Clone()<BR>'    flag = mystru.AppendField(fldinf)<BR>'    flag = pntObj.Att.stru.Set(mystru)<BR>'    Set mystru = Nothing<BR>    <BR>    Set fldinf = Nothing</P>
<P>End If</P>
<P>pntObj.Save<BR>Set pntObj = Nothing</P>
<P>End Sub</P>

vb和VB.NET应该查不多的，出什么错？