Basic Circuit Question

I am trying to debug a kit that I bought that isn't working. I am
trying to test various links on the board with a an LED and resistor
soldered together.

When I hit the put the ends of the LED/resistor at a point on the board
with a direct link to the power supply, it lights up (so the obvious
isn't a problem).

If I move my LED/resistor pair to the next in the chain, a diode I get:

(-V9) ------- (- Diode +) ---- (- LED + ) --- (Resistor) --- (+9V)

and the LED no longer lights. Should I expect it to light up,
suggesting there is a problem with the Diode? Or is there something
more to diode that I am unaware of (I just thought they were one-way
current blockers -- suggesting the above should work).

The Diode is a TN4001. Resistor is 267Ohm. Foward voltage on the LED is
3.7.

.

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