If the new one uses LED's, its important to make sure you have the polarity right, so positive on the bike goes to positive on the blinkers.
Also when changing to LED signals, you often need to replace the flasher relay or they will blink at a very odd rate (sometimes very slow, sometimes very fast)
When you hit the turn signals now, on the dash, do does the turn indicator come on at all? even very faintly, and not flashing?