  An affine Hecke algebras can be realized as an equivariant K-group of the
corresponding Steinberg variety. This gives rise naturally to some two-sided
ideals of the affine Hecke algebra by means of the closures of nilpotent orbits
of the corresponding Lie algebra. In this paper we will show that the two-sided
ideals are in fact the two-sided ideals of the affine Hecke algebra defined
through two-sided cells of the corresponding affine Weyl group after the
two-sided ideals are tensored by rational numbers field. This proves a weak
form of a conjecture of Ginzburg proposed in 1987.
