on slider it is not possible to scroll down the page

I have some sliders created with virtual Portfolio on the page and inbetween some text segments.
Now the problem.
I can not scroll down the page with the track pad if the cursor is on the slider.
I can only scroll the slider left and right.
How can i do both: Left/Right and Up/Down.
Can somebody help?

The page I need help with: [log in to see the link]