如何修改字段的值！这里没人吗？

以下代码！把ZONING这个字段中所有值为"BS"的改为"FL"。<BR>Sub BS_to_FL()<BR>Dim pdoc As IMxDocument<BR>Dim pmap As IMap<BR>Dim play As IFeatureLayer<BR>Dim pfclass As IFeatureClass<BR>Dim pfcursor As IFeatureCursor<BR>Dim pfeature As IFeature<BR>Set pdoc = ThisDocument<BR>Set pmap = pdoc.FocusMap<BR>Set play = pmap.Layer(0)<BR>Set pfclass = play.FeatureClass<BR>Dim qfilter As IQueryFilter<BR>Set qfilter = New QueryFilter<BR>qfilter.WhereClause = "ZONING='BS'"<BR>Set pfcursor = pfclass.Search(qfilter, True)<BR>Set pfeature = pfcursor.NextFeature<BR>While Not pfeature Is Nothing<BR>pfeature.Value(pfclass.FindField("ZONING")) = "FL"<BR><FONT color=red>'pfeature.Store             这一步 为什么不能保存！！！！！</FONT><BR>Set pfeature = pfcursor.NextFeature<BR>Wend<BR><BR>End Sub