typeof yields "wrong name" error

[ren]

ren@mandelbrot:~$ Singular
                     SINGULAR                                 /  Development
 A Computer Algebra System for Polynomial Computations       /   version 4.0.0
                                                           0<
 by: W. Decker, G.-M. Greuel, G. Pfister, H. Schoenemann     \   Dec 2013
FB Mathematik der Universitaet, D-67653 Kaiserslautern        \
> ring r = 0,Y(1..3),dp;
> vector b = -Y(2)*Y(3)*gen(1)+Y(3)^2*gen(1);
> b[1];
-Y(2)*Y(3)+Y(3)^2
> typeof(b[1]);
   ? wrong name, should not happen
   ? error occurred in or before STDIN line 4: `typeof(b[1]);`
> 

[hannes]

cannot reproduce it.