  In this paper, we compute Tian's $\alpha_{m,k}^{K\times K}$-invariant on a
polarized $G$-group compactification, where $K$ denotes a maximal compact
subgroup of a connected complex reductive group $G$. We prove that Tian's
conjecture (see Conjecture 1.1 below) is true for $\alpha_{m,k}^{K\times
K}$-invariant on such manifolds when $k=1$, but it fails in general by
producing counter-examples when $k\ge 2$.
