If you connect the sweep generator output directly to the demod probe, you will get a flat line. This is because the response of the direct connection is flat. It's hard to tell if the equipment is working.
You have to run the sweep through something with a response curve to get anything on the scope.
Here is a sweep I did of the video IF on a CTC15 color set. This was done using the video detector in the set as a detector probe. There are several markers on in the picture, and they are turned up really high. In this case, the markers were injected after the IF strip, so the fact that they are too high doesnt matter much.
I only mention this because if the marker is going through the IF strip you are trying to tune, you need to keep the marker output as low as possible, because it will affect the response curve.
Good luck!
John
P.S. If the pattern is upside down, you can just reverse the polarity on the y-axis or vertical input on the scope. If it is backwards, (higher frequencies to the left) you can reverse the polarity on the x-axis or external sweep input.