If its the move you use with a nunchuk, i got it to work every time i've never had a problem with with it. Maybe you aren't thrusting it forward and maybe your just moving it off to the side, performing the spin attack.Well either way i presume all that will be sorted for Skyward Sword, so no worries there
I think the forward thrust from TP was pretty useless. It was kinda slow for such a simple move and it only hit the enemy directly in front of you and left you open to others around you. I never really found a good use for it.