What have I done -> Blue Cyanamide test

Alrighty so I just did a batch of Calcium Cyanurate, of which I separated into two portions. The first, I heated until red hot, about 900 degrees C I would estimate. The second was heated to a bright orange or yellow, which I'd estimate around 1200 degrees. The photo is of this portion during cooldown. For Cyanamide test, I dissolved some cyanamide in HCl, and added to it a solution of potassium nitrate, silver nitrate, and ammonia. The first solution bubbled vigorously, producing a vapour (H2CN2?) And turned a nice yellow with the silver nitrate solution. The second portion barley bubbled, and produced a deep blue solution with the addition of the Silver Nitrate. My question is; what was made during the second portion? Please help.

My best guess is nitrosyl cyanide (O=N-CN), because it's blue and because we're pretty sure there are CN groups there to form it. That blue color is usually indicative of a nitroso compound.

I figured after this long with no responses, even a guess would be better than nothing.