Just thinking out loud . . have you tried to load and run a simple program?
What I am wondering is if your scope inputs impeadance is so low that the act of checking it loads the oscillator enough to stop it. The "canned" oscillators have a much more robust output than on chip unit. try putting an 100 kilo to 1 meg ohm resistor in series with your input, it will reduce the pattern height but if you geet anything on screen then you know you are on track. . .
JS