Code:
mainloop:
Pause 10
if PortA.5= 1 then PortB.1 = 1 'turn ON an LED
if PortA.5= 0 then PortB.1= 0 'turn OFF an LED
goto mainloop
Reduce the value of your pullup resistor from 100k to 10k and add a delay in the loop as per the above example.

Then it should work as you expected.

Cheers

Al.