VNC + DOS application = black screen

Hi! Could anyone help me? I’m running UltraVNC and RealVNC and I have broblem… VNC works just fine if I use it on Windows applications but if I try to connect to remote computer which is running DOS application I only see black screen. I’d appreciate any kind of tip that I could use to solve this problem. I’m in a deep poo if there’s no way I can see DOS application on a remote computer using VNC client. Thanks in advance!

Is this a DOS-application running under Windows, or a native DOS system?

DOS-application is running under W2k and on Win98. I need them both to work.

And you have the same problem with both W2K & Win98? Is the app running full-screen, or windowed?

Yes, the problem is the same on both systems. App is running on full-screen.

And if you run the app in windowed mode? Does that work? Does the app use text-mode, or some graphics mode?

The app is a cash register program and can only be run in full screen mode. App is textmode only.