[求助]把54坐标系转成经纬度出现错误,invalid bounds specified

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<TD  width="100%"> <B>[求助]把54坐标系转成经纬度出现错误,invalid bounds specified</B><BR>[求助]把54坐标系转成经纬度出现错误,invalid bounds specified<BR>请大侠帮忙看看!是不是参数位置放错了?
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<P>procedure TForm1.change54toxy(nGisX, nGisY: Double);<BR>  var<BR>    oDtm: MapXLib_TLB.Datum;<BR>    nJwdX,nJwdY: Double;<BR>    nTmpX,nTmpY: Single;<BR>begin<BR>  oDtm:=MapXLib_TLB.CoDatum.Create;<BR>  //把MAP设为GIS坐标系<BR>  oDtm.Set_(3, 24, -123, -94, -0.02, 0.25, 0.13, 1.1, 0);</P>
<P>  map1.NumericCoordSys.Set_(8,oDtm,7,0,0,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,1,500000,0);</P>
<P>  map1.MapUnit:=miUnitMeter;</P>
<P>  //GIS坐标系点转为屏幕点<BR>  map1.ConvertCoord(nTmpX, nTmpY, nGisX, nGisY, miMapToScreen);<BR>  //把MAP设为经纬坐标系<BR>  map1.NumericCoordSys.Set_(1, 0,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam,EmptyParam);<BR>  map1.MapUnit := miUnitDegree;<BR> //屏幕点转为转为经纬系点<BR>  map1.ConvertCoord(nTmpX, nTmpY, nJwdX, nJwdY, miScreenToMap);<BR>  Edit3.Text:=floattostr(nJwdX);<BR>  Edit4.Text:=floattostr(nJwdY);<BR>end;</P>
<P><BR>procedure TForm1.Button1Click(Sender: TObject);<BR>begin<BR>  change54toxy(493705.185,3172066.712);<BR>end;</P></TD></TR></TABLE>

<P><STRONG>invalid bounds specified</STRONG><BR>意思应该是：指定范围无效</P>