Asset file couldn't attach.

[shariful2011]

I am trying to share an assets file but the file is not attaching, please see the attached image.
This is what I did for making a copy of asset's file in temp path:

Directory tempDir = await getTemporaryDirectory();
String tempPath = tempDir.path;
//fileName = assets folder's filename
String filePath = join(tempPath, fileName);

ByteData data = await rootBundle.load(join(assetPath, fileName));
List<int> bytes =
    data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
await File(filePath).writeAsBytes(bytes);

[KaYBlitZ]

Getting the same error using temporary directory as well. File will not attach.