求助：[附源代码]

<P>我想从数据库里读取数据(如经度纬度)后,将某一图元(如车辆)加载到这一点,用的是VB+MapX+SQL Server,用ToolUsed事件可以,用控件按钮点击时就不行了，请大家指点指点，一下是源代码：</P>
<P>Private Sub ShowCar_Click()</P>
<P>    Dim carx As Double           '车辆经度/纬度坐标<br>    Dim cary As Double<br>    Dim cnn As ADODB.Connection   '数据库定义<br>    Dim rst As ADODB.Recordset<br>    Dim connectstring As String<br>    Dim strSQL As String<br>   'Create a temporary layer and make it the animation layer.<br>    Set lyrMyLayer = Map1.Layers.CreateLayer("Cars", , 1)<br>    Set Map1.Layers.AnimationLayer = lyrMyLayer<br>    lyrMyLayer.LabelProperties.Overlap = True<br>    '打开数据库联接<br>    connectstring = "driver={SQL Server};Server=127.0.0.1;uid=sa;pwd=123456;database=GIS"<br>     Set cnn = New ADODB.Connection<br>     cnn.Open connectstring  '打开数据库，以便rst操作数据库<br>     strSQL = "select * from NewestInfo "<br>    Set rst = New ADODB.Recordset<br>    rst.Open Trim$(strSQL), cnn, adOpenKeyset, adLockOptimistic<br>    rst.MoveFirst<br>carx = rst("Longitude")<br>cary = rst("Latitude")</P>
<P>rst.MoveNext</P>
<P>Dim fNewSymbol As mapxlib.Feature<br>Dim fMapSymbol As mapxlib.Feature<br>Dim pt As New Point<br>Dim NewStyle As mapxlib.Style<br>Set NewStyle = New mapxlib.Style<br>With NewStyle<br>.SymbolType = miSymbolTypeBitmap<br>.SymbolBitmapSize = 24<br>.SymbolBitmapTransparent = True<br>.SymbolBitmapName = "FIRE1-32.BMP" ' 图元名称<br>End With<br>pt.Set carx, cary<br>Set fNewSymbol = Map1.FeatureFactory.CreateSymbol(pt, NewStyle)<br>Set fMapSymbol = lyrMyLayer.AddFeature(fNewSymbol)</P>
<P>End Sub<br></P>

<P>是不是没刷新?</P>
<P>refresh</P>

好象carx,cary未赋值