  We show that $\frac{\Gamma(f_0,f_1,\dots,f_m)}
{\Gamma(f_1,\dots,f_m)}=\infty$ for $m+1$ vectors having the properties that no
non-trivial linear combination of them belongs to $l_2(\mathbb N)$. This
property is essential in the proof of the irreducibility of unitary
representations of some infinite-dimensional groups.
