ERROR IN ANSYS(EIGEN BUCKLING)

HI

i am traying to create buckling(eigen buckling)in ansys ver10.for contilever beam i haven't any problem,but in another types(for example beam with pin ends and etc)program have a similer error by this notification.ALL STIFFNESS MATRIX IS ZERO

please if it's possible help me

BEST REGARDS

HAMID ABEDI