problem with building nanotube supercell

[zhuyt]

I want to build the carbon nanotube supercell with keyword “supercell ”， unfortunately， the crystal reports errors：“**** MULTIP **** SYMMOPS DO NOT FORM A GROUP ”
the INPUT file:
TEST07_1 - armchair C NANOTUBE - 6-21G, PBEsol
SLAB
77
2.47
1
6 -0.33333333333 0.33333333333 0.
SWCNT
5 5
supercell
2
end