Proof of W.M.Schmidt's conjecture concerning successive minima of a lattice

For a real $N\ge 1$ and a vector $\xi =(1,\xi_1,...,\xi_n)$ define a matrix {\cal A} (\xi, N) = ({array}{ccccc} N^{-1} & 0& 0& ... &0 \cr N^{\frac{1}{n}} \xi_1 & -N^{\frac{1}{n}} & 0&... & 0 \cr N^{\frac{1}{n}} \xi_2 &0& -N^{\frac{1}{n}} & ... & 0 \cr ... &... &... &... \cr N^{\frac{1}{n}} \xi_n &0&0&... &- N^{\frac{1}{n}} {array}) and a lattice $$\Lambda (\xi, N) = {\cal A} (\xi, N)\mathbb{Z}^{n+1}.$$ Consider a convex 0-symmetric body $${\cal W} = \{z= (x,y_1,...,y_n)\in \mathbb{R}^{n+1}: \max (|x|, |y|)\le 1 \} >.$$ For a natural $l, 1\le l \le n+1$ let $\mu_l (\xi, N)$ be the $l$-th successive minimum of ${\cal W}$ with respect to $\Lambda (\xi, N)$. We prove that there exist real numbers $\xi_1,...,\xi_n$ linearly independent together with 1 over $\mathbb{Z}$, such that $\mu_k (\xi, N) \to 0$ as $N\to \infty$ and $\mu_{k+2} (\xi, N) \to \infty$ as $N\to \infty$.Comment: Submitted to Proceedings of LMS, further minor correction