Certain files won't open once transferred via FTP

I have a very basic console app which I've developed in C++-CLI. All the app does is transfers files to a ftp server. Each file gets transfered as required. I can open

.jpeg .png .gif

But when I try to open .docx or .xlsx I get the following error message

below is the relevant snippet of code

const int bufferLength = 2048;
    array<Byte>^buffer = gcnew array < Byte >(bufferLength);
    int count = 0;
    int readBytes = 0;
    FileStream^ stream = File::OpenRead(originalDirPath + e->Name);
    do
    {
        readBytes = stream->Read(buffer, 0, bufferLength);
        requestStream->Write(buffer, 0, bufferLength);
        count += readBytes;
    }
    while (readBytes != 0);
    Console::WriteLine("Writing {0} bytes to the stream.", count);

I can't seem to figure out where I'm going wrong