  In this paper we show that the leading coefficients $\mu(y,w)$ of some
Kazhdan-Lusztig polynomials $P_{y,w}$ with $y,w$ in the affine Weyl group of
type $\widetilde{B_n}$ can be $n$; in the cases of types $\widetilde{C_n}$ and
$\widetilde{D_n}$ they can be $n+1.$ Consequently, for the corresponding simply
connected simple algebraic groups, the dimensions of the first extension groups
between certain irreducible modules will go to infinity when $n$ increases.
