I set the temperature on my Mini mat to 65 degrees, with a 3-D protector under me, but I do not sweat. Can you tell me what I am doing wrong?

Larger mats as Professional or Compact Pro work faster for sweating as they are more powerful and have higher surface area contacting your body. 

Mini mats are not the most efficient to cause sweating; they are better for focused heating of specific parts of your body. But if you use a high temperature and your body usually sweats in the sauna or does sports or work out, the Mini will work fine.

Use the thinner waterproof cover, drink a cup of hot tea, cover it with a blanket, preheat your Mini mat to the maximum level, lay on it, and relax. 

Make sure you cover your body completely except your head with a thick blanket. No other parts of your body should be uncovered. You will sweat as if you were in the sauna in 30-45 minutes.

If your body is not familiar with training and is not used to sweating, it is quite normal if it takes a month or so before you sweat for the first time. 

Just remember to drink a lot of mineral water before, during, and after sessions.