problem in cloth modifier

[athenak]

hi everyone

i have a problem with cloth modifier.

i want roll up my Curtain triangular.after i apply garment modifier and cloth

I'm following these steps:make 2 cylinders,then

place them along the sides,

make group of vertex for my triangular and surface them to cylinders

then set the frame on 100 active auto key

and use scale for shrink cylinders

but

when i click on simulat ,disappear my curtain ?

can u help me to say why this happend and what should i do?