Problem with volume sampler !!!!

hello friends,
I have a problem with the volume sampler, pressing the button the volume sampler is out of control and when I press several times the volume up and down. here is a video sample.
http://youtu.be/5Om0Y0wOJ7s
how do I program the sampler?, commands or settings that I take to prevent this from happening?
I need the volume is always 100%
Help please!
Thanks and sorry for my English, (I'm using a translator)
I have a problem with the volume sampler, pressing the button the volume sampler is out of control and when I press several times the volume up and down. here is a video sample.
http://youtu.be/5Om0Y0wOJ7s
how do I program the sampler?, commands or settings that I take to prevent this from happening?
I need the volume is always 100%
Help please!
Thanks and sorry for my English, (I'm using a translator)