The only way I see your circuits working as drawn is by the base-emitter reverse breakdown voltage having been achieved so that the current from the sensor goes directly through the transistor towards the LED without being amplified. Chances are that your supply voltage is higher than 5V. <br>
 The only other possibility is that you have mistakenly reversed the emitter and collector pins (and got them connected properly, unlike the schematic).
 As for your intended circuit, I think you could just stick with an NPN as indicated in the 555 schematic, but you could also use a PNP transistor while connecting its emitter to the V+ supply side and the bulb between 0V and the collector. <br>