Trinary Calculator, good idea?

[Frontrider]

Hmm, the design looks really really familiar. Slightly altered hex adder where you ckeck the output if its a possible result. If yes, than it will make it through if not then it won't. You don't need input check as long as you stay bellow 7.

I tried to copy the design, but something is wrong. Can you ckeck my plot? (Frontryder) I might be wrong but the signal strenght of 3 on the top should be 12.