Runtime error: Unimplemented FFish Script bytecode, by tianlang

[SWFKit]

what meaning this error:
Runtime error: Unimplemented FFish Script bytecode.

It's will happen when after download 100%. follow is code:

//ftpDownload

fileSave();
function fileSave()
{
downloadFile=FlashPlayer.getVariable("_root.downlo adFile");
var file=Dialogs.fileSave("All files(*.*)|*.*|","",downloadFile); //trace(file);

if(file!=undefined)
{
//OnFTPDownloadEvent("0||"+filename);
ftpDownload(downloadFile,file);
}
else
{
OnFTPDownloadEvent("1")
}
}

function OnFTPDownloadEvent(info)
{
trace("OnFTPDownloadEvent:"+info);
FlashPlayer.setVariable("OnFTPDownloadEvent.fArg", ""+info);
}

function ftpDownload()
{
var ftpServer=FlashPlayer.getArray("_root.ftpServer");
ftpDownload = Inet.openFtp(ftpServer[0],ftpServer[1],ftpServer[2],"123");

if(ftpDownload.connect())
{
OnFTPDownloadEvent("2");
ftpDownload.onDownload = function (percent)
{
OnFTPDownloadEvent("4||"+percent+"%");
if (!processMsg()) return false;

if(percent==100)
{
ftpDownload.close();
OnFTPDownloadEvent("6");
}
return true;
}
ftpDownload.download(arguments[0],arguments[1]);
}
else
{
OnFTPDownloadEvent("3");
ftpDownload.close();
}
}

function ftpDownloadCancel()
{
OnFTPDownloadEvent("5");
ftpDownload.close();
}

[SWFKit]

Please send us the source file (support@swfkit.com). Thank you.