vb.net中使用接口问题

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<TD class=subtitle colSpan=6>内容摘要</TD></TR>
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<TD class=txt colSpan=6>以前有一段在8.3下面写的代码，是用于获取某字段独立值的，如下：
Public Function lstUniqueValue(ByVal pFeatClass As IFeatureClass, ByVal pFieldName As String) As Collection
Dim i As Long
Dim lCount As Long
Dim pValue As Object

Dim pDataStat As ESRI.ArcGIS.Geodatabase.IDataStatistics
Dim pFeatCursor As IFeatureCursor
Dim pEnumVar As IEnumVariantSimple

Try
lstUniqueValue = New Collection
pFeatCursor = pFeatClass.Search(Nothing, False)
pDataStat = New ESRI.ArcGIS.Geodatabase.DataStatistics
pDataStat.Field = pFieldName
pDataStat.Cursor = pFeatCursor
pEnumVar = pDataStat.UniqueValues
lCount = pDataStat.UniqueValueCount
If lCount <> 0 Then
For i = 0 To lCount - 1
pValue = pEnumVar.Next()
lstUniqueValue.Add(pValue)
Next
End If
Catch ex As Exception
lstUniqueValue = Nothing
MsgBox("错误描述：" ; ex.Message)
End Try

pDataStat = Nothing
pFeatCursor = Nothing
pEnumVar = Nothing
End Function

现在在vb.net下似乎pDataStat.UniqueValues的UniqueValues方法与net框架的同名方法冲突，我加了定义限定仍然不行，提示错误是“类型无法转换”，请问该如何解决这个问题
其实也可以用很笨的循环判断的方法，但这个方法效率很高，我们想将这个程序调通
谢谢。</TD></TR>
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<TD class=subtitle colSpan=6>过程描述</TD></TR>
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<TD class=txt colSpan=6>只要将Dim pEnumVar As IEnumVariantSimple 改为Dim pEnumVar As System.Collections.IEnumerator即可。
如下：

Dim pEnumVar As System.Collections.IEnumerator

Try
lstUniqueValue = New Collection
pFeatCursor = pFeatClass.Search(Nothing, False)
pDataStat = New ESRI.ArcGIS.Geodatabase.DataStatistics
pDataStat.Field = pFieldName
pDataStat.Cursor = pFeatCursor
pEnumVar = pDataStat.UniqueValues
lCount = pDataStat.UniqueValueCount
If lCount <> 0 Then
For i = 0 To lCount - 1
pValue = pEnumVar.MoveNext()
lstUniqueValue.Add(pValue)
Next
End If
Catch ex As Exception
lstUniqueValue = Nothing
MsgBox("错误描述：" ; ex.Message)
End Try</TD></TR></TABLE>

呵呵，不错，有时间我试试！