[求助]增加图元时，出现了图层不可编辑的错误？

<P>我刚刚开始学习mapX大家指导一下吧</P>
<P>procedure TForm1.Map1ToolUsed(ASender: TObject; ToolNum: Smallint; X1, Y1,<BR>  X2, Y2, Distance: Double; Shift, Ctrl: WordBool;<BR>  var EnableDefault: WordBool);<BR>var<BR>  pt:CMapXPoint;<BR>  Lyr:CMapXLayer;<BR>  ftr:CMapXFeature;<BR>  feaFac:CMapXFeatureFactory;<BR>  newStyle:CMapXStyle;<BR>begin<BR>  //邦定<BR>  lyr:=Map1.Layers['China Major cities'];<BR>  feaFac:=map1.FeatureFactory;<BR>  //设置点对象样式<BR>  newstyle:=CoStyle.Create;<BR>  newstyle.SymbolType:=miSymbolTypeBitmap;<BR>  newstyle.SymbolBitmapSize:=24;<BR>  newstyle.SymbolBitmapTransparent:=false;<BR>  newstyle.SymbolBitmapName:='YIEL2-32.BMP';<BR>  //禁止自动刷新<BR>  Map1.AutoRedraw:=false;<BR>  //置当前图层为可写状态<BR>  lyr.Editable:=true;<BR>  //创建点对象<BR>  pt:=CoPoint.Create;<BR>  pt.Set_(map1.CenterX,map1.CenterY);<BR>  //添加进当前图层<BR>  ftr:=feafac.CreateSymbol(pt,NewStyle); //创建符号<BR>  ftr:=feafac.CreateSymbol(pt,map1.DefaultStyle);<BR>  //添加<BR>  lyr.AddFeature(ftr,EmptyParam);<BR>  lyr.Refresh;<BR>  map1.AutoRedraw:=true;<BR>  lyr.Editable:=false;<BR>  //释放<BR>  pt._Release;<BR>  newStyle._Release;<BR>end;</P>