You need to set the shutter speed via the interface of the Remote Pro application, not directly on your camera. The camera is probably reverting to "Bulb" mode because the application is telling it to do so. The application, rather than the camera, will then provide the timing function. It will be similar to when using a remote cable release with the camera set to "Bulb": pressing the button on the remote for 1/125 second will result in a 1/125 second exposure, pressing the button for 1/2 second will result in a 1/2 second exposure, etc. You probably also need to set aperture and ISO via the application.

With a wired remote most of us are not precise enough to time "Bulb" exposures that are shorter than several seconds accurately enough. Your computer application, however, should be perfectly capable of timing the shutter command precisely enough to use shutter times up to the camera's sync speed when the camera is in "Bulb" mode.