I added a mezzanine that extends above the roof of my house. The roof is metal and the roofer suggested i insulate it with foam to reduce the chances of condensation. I have sprayed about 2 inches of foam. I have also batts of r22 that i have put in. The problem i have is with or without the batts i have a condensation problem and im not sure what to do to stop it. I dont want to close the celing for fear of aq mositure problem. I am i a relatively cold climate(montreal, Canada) What do i do? should i add more insulation, foam or batts, with the drywall and vaporbarrier save me or help? Or should i not have a vapor barrier because i have used foam directly to the underside of the roof?......help

2" of foam is not going to do anything.
I assume you did the foam youself? Perhaps with the canned stuff? If so you need to go back to step one. The foam used must fill the entire cavity not just a small part. Mixing the stuff up will not work foam and fiberglass. The primary reason for the foam is the ability to stop vapor tranmission better then the basic vaor barrier installed with fiberglass. Fiberglass will not do this unless you have a perfect vapor barrier. Also because the area in which you live is so cold the amount "R Factor" of insulation needed is much higher then the most of the lower U.S. Add to that the metal roof, which transmits cold faster then a shingle roof and you need even more R value.
The Vapor barrier should be towards the heated side of the house.
To understand why this is the inside has the humidity. Moisture always moves towards a space which is dryer. It will go through just about all materials except most plastics, most foam, steel, glass. The outside during the winter is very dry. Even with snow on the ground. What moisture is around feezes.
As the vapor pressure in the house is higher then the outside the moisture moves through the walls, ceilings. As it does it moves through the fiberglass insulation as well. Once this moves through the insulation it goes towards the outside of the house where the insulation begins to become cooler. Eventually it reaches the dew point. Which is a point where the vapor condenses to condensate. You must stop this by providing enough insulation to create a barrier in which the cold side never reaches the warm side. And also provide a very good vapor barrier to prevent the vapor to travel through to the the cold side of the wall. Faom does this very well. But it has to be the entire thickness of the wall or at least very close to the thickness of it.

Depending on the debth of the ceiling joists/rafters and the requirements for R value in the area in which you live. Will determine what method of insuation you should be using.

Also controling of interior humidity will also help. with todays new construction codes homes are built tighter then before. Thus more humidity builds up and ends up causing more problems.

I hope this explains things a bit for you. Once you understand how the condensation forms the easier it is to come up with a solution that will prevent it from happening.
I am sure there will be other folks that understand foam better then I, and will chime in with some more useful facts. But they all follow the same rules with vapor transmision. stop the moisture from reaching the cooler side of the wall. And stop the cooler side from reaching the warm side of the wall.