Using Set command to specify Fraction of atoms in a system having more than two types of atoms

I am currently working on a polydisperse LJ system. I want to incorporate discrete polydispersity in my system by setting number fractions of various types of atoms.

The Set command I am using for this purpose has the following form:
set group all type/fraction 2 0.1 1000
set group all type/fraction 3 0.1 1099

The settings are being made only for the 3rd type of atoms while for the 2nd they are being disregarded.

Please tell me a way to get around this problem.

Vyom Vats,
LAMMPS user.

If I add those 2 lines to bench/in.lj and allow
for 3 atom types, it seems to work fine.

Script is below.

Steve

# 3d Lennard-Jones melt

units lj
atom_style atomic

lattice fcc 0.8442
region box block 0 10 0 10 0 10
create_box 3 box
create_atoms 1 box
mass * 1.0

velocity all create 1.44 87287 loop geom

pair_style lj/cut 2.5
pair_coeff * * 1.0 1.0 2.5

neighbor 0.3 bin
neigh_modify delay 0 every 20 check no

fix 1 all nve

set group all type/fraction 2 0.1 1000
set group all type/fraction 3 0.1 1099

run 100