[PyMOL] visualization problems with pymol

Hi pymol users!

I installed pymol in a Windows 7 (32 bits). I can load a file without
problems to pymol but when i try to change the lines for sticks the
molecule (a .sdf file)  disappear ... so i have been trying to change the
representations but pymol online recognize lines.
Did anyone knows how to fix it ?

Thanks a lot
Carolina Castro