Dogs can play off your emotions too. Are you as relaxed at the line as you would be on a normal training day? It's hard to expect the dog to act like nothing is different if your heart is pounding 200 bpm and your hands are shaking.
Seriously, if you are nervous, you are probably rushing things at the line and may not giving him a chance to 'see' the test before releasing him.
Seriously, if you are nervous, you are probably rushing things at the line and may not giving him a chance to 'see' the test before releasing him.