三层上传文件时，第一次上传正常，第二次上传客户端会报内存错误，第三次上传又正常，请帮我看看是什么原因？


服务端代码：
[code delphi]
function TServerMethods1.PutFile(AfileName,SaveFolder: string; Stream: TStream): Boolean;
const //上传
BufSize = $F000;
var
Buffer: TBytes;
ReadCount: Integer;
FS: TFileStream;
begin

if not DirectoryExists(AppPath SaveFolder) then
CreateDir(AppPath SaveFolder);
try
FS := TFileStream.Create(AppPath SaveFolder AfileName, FmCreate);
if Stream.Size = -1 then // 大小未知则一直读取到没有数据为止
begin
SetLength(Buffer, BufSize);
repeat
ReadCount := Stream.Read(Buffer[0], BufSize);
if ReadCount > 0 then
FS.WriteBuffer(Buffer[0], ReadCount);
if ReadCount < BufSize then
break;
until ReadCount < BufSize;
end
else // 大小已知则直接复制数据
FS.CopyFrom(Stream, 0);
Result := True;
FMan.Insertlog('客户端上传文件成功：' AppPath AfileName);
Except
FMan.Insertlog('客户端上传文件失败：' AppPath AfileName);
Result := False;
end;
FreeAndNil(FS);
end;
[/code]

客户端上传调用代码：
[code delphi]
Function TDtM.PutFile(faName,toName: String):Boolean;
var aSeream:TStream;
begin
try
aSeream:=TStream.Create;
aSeream:=TfileStream.Create(faName,fmShareDenyNone);
Result:=aiapp.PutFile(toName,'file\',aSeream); //这一行在第二次上传时会报内存错误。

Except
end;
FreeAndNil(aSeream);
end;
[/code]