Super ten shifting on grades, what am I doing wrong?

I just got my license not to long ago and have started driving with the super ten transmission and so far it's real easy exept for when I go to take off on a grade. What happens sometimes is when I go to do a button shift it will go in to neutral and cause me to almost stop or down shift. It only does it if the engine is pulling hard. So what do y'all think I am doing wrong? I have driven a 15 and ten speed and seem to have the hang of that so I had to get used to the super ten. Thanks in advance for your advice.

 

Thanks the video helps a lot. I think what i miss sometimes is I'll forget to let all the way off the fuel and then it misses the shift. If it makes any difference I leave my Jakes on high all the time.

 

Thanks for all the input. So the way I was shifting was pre selecting the button and on a hard pull as soon as I let out it would go into nuetral and grind so I'll try waiting till I've made my lever shift to flip the button and ease my shifts. Should I be using the clutch for a button shift? I usually don't use the clutch to shift but not sure if it would help