Have you tried replacing the 47K resistor with a 10K as somebody
suggested earlier? Methinks the 47K is to high and the input is
floating, possible oscilating with interference causing your led's to
switch on and of fast (you don't see it). Yellow will turn on because
you are taking the pin to ground. A shot in the dark here. Also, what
happens if you take the switch to +V and the resistor to ground does the
green come on then and maybe not the yellow?
Also, you only need 1 NOP instruction between the switching.

Quentin

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