  An ideal projector on the space of polynomials $\mathbb{C}
[\mathbf{x}]=\mathbb{C} [x_{1},\ldots ,x_{d}]$ is a projector whose kernel is
an ideal in $\mathbb{C}[ \mathbf{x}]$. The question of characterization of
ideal projectors that are limits of Lagrange projector was posed by Carl de
Boor. In this paper we make a contribution to this problem. Every ideal
projector $P$ can be written as a sum of ideal projector $\sum P^{(k)}$ $\
$such that $\cap \ker P^{(k)}$ is a primary decomposition of the ideal $\ker
P$. We show that $P$ is a limit of Lagrange projectors if and only if each
$P^{(k)}$ is. As an application we construct an ideal projector $P$ whose
kernel is a symmetric ideal, yet $P$ is not a limit of Lagrange projectors.
