How to obtain the eigenvector for the following graph?

savecancel

Here is some code:

G=graphs.EmptyGraph()
G.add_edges([(1,2),(2,3),(2,4),(1,6),(1,5)])
G.show()
l=G.laplacian_matrix()
show(l)
g=l[[1,2,3,4,5],[1,2,3,4,5]]
d=~g
show(d)
t=d[[0,1,2],[0,1,2]]
show(t)
Q=matrix(QQ,3 , 3, lambda x, y: 1)
e=t-0.5*Q
z=e.eigenvectors_right()
z.sort()
show(z)

My eigenvectors are not coming and sage is giving some error report. How to recover it?