Where in the line up should a Boss Noise Suppressor Pedal be placed on a pedal board for maximum effect ?

The probable problem is poor connections at the input and/or audio output jacks.

Usually the power supply will fail either on or off which is sometimes cause by a bad input power jack.

In any case, the problem is likely internal and will require repair.

It is possible the pedal is DESIGNED to be used with an amplified (preamp within guitar) and yours MAY be a passive guitar. You did not tell us what guitar you have.
Many of the processors for guitars depend on having a "line level" signal and that requires that your guitar has a built in preamp.
If your guitar doesn't have a preamp in it, buy a preamp to put ahead of this pedal.

First, make sure the jack is not shorting against the circuit board or an adjacent wire. Check the wire connections at the jacks and switch. Sometimes these wires disconnect due to poor solder joints on the switch or jacks. Make sure the circuit board is not touching the enclosure or pot assembly.

Here is the schematic:http://www.godiksennet.com/images/sch/NS2.jpg Try testing or replacing Q1 first.

First and foremost , check your signal chain. By that, i mean put the pedal aside, ...just unhook it and take it out of your signal path. Using the same cables , guitar , amp, other pedals - borrow a friends MT-2 if you can get one , and try THAT to see if THAT works , OR any other kind of distortion pedal. If another one works ok , it's YOUR MT-2. Boss pedals are pretty rugged , but sometimes the little actuator (on/off switch) underneath the treadle (where you push your foot down) will become faulty. That's a high-gain pedal - are you using a basic Strat or other single-coil pickup guitar? If so , are you playing close to any flourescent lights? SIngle coils are noisy around those lights. Will cause a hum / buzz if using a heavy dist. pedal. You can check that by moving around as you play.

The Roland requires a NORMALLY CLOSED contact and that usually cannot be changed.

You will need to reverse the contacts in your pedal to meet that requirement.

OFTEN the pedals have BOTH contacts and you just have to unsolder and move the wire to the opposite contact. This is a common problem

The power jack on MANY of the pedals are weak and a yank sideways can damage the jack or the board it is mounted on.

ANOOTHER problem is using an adapter with the wrong size plug. SOME plugs have a larger diameter hole and will work intermittenly.

Here is the retrevo site that has the manual with connection diagram.

http://www.retrevo.com/d/ds/progress?doc=e2d5b73911466148a2b8b5e8a93e4a62

With everything switched off. I will surmise that you are using the onboard battery with the foot pedal and not a power supply.
1. Plug lead from guitar/instrument into INPUT side of pedal
2. Plug lead from OUTPUT side of pedal into amplifier INPUT.
3. Turn amplifier volume to about 10 o'clock - to stop blowing your ears out.
4. Turn volume up on guitar to acceptable level.
5. press foot switch on pedal and adjust pedal controls to suit your type of distortion.
6. Play like Hendrix.
Good Luck
ps Just as an after thought rechargeable 9volt batteries are the way to go. I've been using them for years as I always get caught up in the power cable.
If you're going to add another pedal like a Phaser, Compressor, Flanger or what just use small connect leads between each pedal but always, always put the compressor pedal last in the line.

Yes. Very much so. The noise reduction should be the very last pedal, of course. Try to even plug your chain in a different outlet than the one your amp (or if recording to a computer, different than the computer outlet). If you have a particularly loud distortion, have it be the last one before the noise reduction pedal.