Magic Carpet problems..

[absmonster]

Im having this problem with the magic carpet, when ever my friends uses it (not when i use it) it will disappear after they have jumped 3 times on it so everytime they want to go up they will fall down, im the only one that can use it properly :/ i have tryed giving them the same permissions and me and stuff but it just wont work for them..
anyone got a fix?