用TIdTcpServer主动断开客户端的OnExecute中的ReadFromStack(true,100,false)老出现这个错误'Not Connected'

Indy版本:9.00.10

断开代码：

if not AThread.Terminated then
begin
AThread.Terminate;
end;
except on Ex : Exception do
AppendLog(inttostr(TCPPort) ' 结束客户端线程 失败(DisconnectTCPClient),ErrorInfo : ' Ex.Message);
end;
try
if AThread.Connection.Connected then
begin
AThread.Connection.CheckForGracefulDisconnect(true);
AThread.Connection.Disconnect;
end;
except on Ex : Exception do
AppendLog(inttostr(TCPPort) '断开客户端连接 失败(DisconnectTCPClient),ErrorInfo : ' Ex.Message);
end;

OnExecute部分代码：

AThread.FreeOnTerminate := true;
if (not AThread.Terminated) and (AThread.Connection.Connected) then
begin
tmpBufferLen := 0;
try
if AThread.Connection.Connected then
begin
tmpBufferLen := AThread.Connection.ReadFromStack(true,100,false);/就这出现错误'Not Connected'
end;
except on Ex : Exception do
begin
DisconnectTCPClient(AThread);
AppendLog(IntToStr(TCPPort) '; TCPServerExecute ReadFromStack Error : ' Ex.Message);
end;
end;

......
end;

请问什么原因？如何解决？

msn:ansili@hotmail.com