multiple read data command

I use 2015 version of lammps, but I can not use “read_data add append command” for reading second data file,
because when I use this command, lammps gives error: Illegal read data command
can you help me?
my input script:

boundary p p p
units metal
atom_style full
read_data data.cc3r

pair_style lj/cut 22
pair_modify mix arithmetic
pair_coeff

bond_style class2
bond_coeff

angle_style class2
angle_coeff

dihedral_style class2
dihedral_coeff

neigh_modify delay 0 every 1 check yes page 1000000 one 20000
special_bonds charmm

timestep 0.001

fix myfix1 all nvt temp 300.0 300.0 0.1
run 500

minimize 0.0 0.0 10000 400000
min_style cg
min_modify dmax 0.1

clear
boundary p p p
units metal
atom_style full

read_data data.mer1 add append
pair_style lj/cut 22
pair_modify mix arithmetic
pair_coeff

bond_style class2
bond_coeff

minimize 0.0 0.0 10000 400000
min_style cg
min_modify dmax 0.1

fix myfix3 all npt temp 300.0 300.0 0.1 iso 1.0 1.0 0.1
run 3000

I use 2015 version of lammps, but I can not use "read_data add append

there have been 81 different patchlevel releases of LAMMPS in 2015,
you have to be a bit more accurate.

command" for reading second data file,
because when I use this command, lammps gives error: Illegal read data
command
can you help me?

have you tried a more recent version of LAMMPS? the option to use
read_data multiple times is a rather new feature.

axel.