Delphi XE和ZLib问题

我正在尝试压缩一些字符串(并对其进行编码以通过SOAP Web服务发送 – 非常重要 – )

来自ZDecompressString的字符串结果与ZCompressString中使用的不同.

例1：

uses ZLib;
// compressing string
// ZCompressString('1234567890',zcMax); 
// compressed string ='xú3426153·°4'

// Uncompressing the result of ZCompressString,don't return the same:
// ZDecompressString('xú3426153·°4'); 
// uncompressed string = '123456789'

if '1234567890' <> ZDecompressString(ZCompressString('1234567890',zcMax)) then
  ShowMessage('Compression/Decompression fails');

例2：

Uses ZLib;
// compressing string
// ZCompressString('12345678901234567890',zcMax) 
// compressed string ='xú3426153·°40?3'

// Uncompressing the result of ZCompressString,don't return the same:
// ZDecompressString('xú3426153·°40?3') 
// uncompressed string = '12345678901'

if '12345678901234567890' <> ZDecompressString(ZCompressString('12345678901234567890',zcMax)) then
  ShowMessage('Compression/Decompression fails');

使用的函数来自其他一些关于压缩和解压缩的帖子

function TForm1.ZCompressString(aText: string; aCompressionLevel: TZCompressionLevel): string;
var
  strInput,strOutput: TStringStream;
  Zipper: TZCompressionStream;
begin
  Result:= '';
  strInput:= TStringStream.Create(aText);
  strOutput:= TStringStream.Create;
  try
    Zipper:= TZCompressionStream.Create(strOutput,aCompressionLevel);
    try
      Zipper.CopyFrom(strInput,strInput.Size);
    finally
      Zipper.Free;
    end;
    Result:= strOutput.DataString;
  finally
    strInput.Free;
    strOutput.Free;
  end;
end;

function TForm1.ZDecompressString(aText: string): string;
var
  strInput,strOutput: TStringStream;
  Unzipper: TZDecompressionStream;
begin
  Result:= '';
  strInput:= TStringStream.Create(aText);
  strOutput:= TStringStream.Create;
  try
    Unzipper:= TZDecompressionStream.Create(strInput);
    try
      strOutput.CopyFrom(Unzipper,Unzipper.Size);
    finally
      Unzipper.Free;
    end;
    Result:= strOutput.DataString;
  finally
    strInput.Free;
    strOutput.Free;
  end;
end;

哪里错了？

有人有同样的问题吗？