Cutting woven cloth

Hi all
Please help me this is my first post,dont even know if i am in the right place.
We bought an Ultra sonic knife to cut carbon fiber,kevlar,carbon/kevlar hybrid and glass all raw cloth.
My knife does not seem to do the trick to cut these.The moment i start cutting i loose vacuum and the strands of the material starts pulling apart without being cut.

use a masking tape where you are cutting both sides of the matt and cut within tha taped area.

did you come right with the cutter ?