make sure the generator is set up so the low is around 0 volts and the
high is around +5 (Note that is not the same as 5vp-p becuase 3 to 8
is also 5 volts p-p but would be wrong)

If the generator can drive a 0 volts to +5 volt pulse into a grounded
50 Ohm resistor but not into your gate, then you have the gate hooked
up wrong or the gate is bad.

Mark