how to dump compute msd

I'm having a problem with msd computation and dumping it into file.

My input is:

units metal
atom_style atomic

boundary p p p

lattice fcc 3.9200
region box block -50 50 -50 50 -50 50 units lattice
create_box 1 box

lattice fcc 3.9200
region PtDrop sphere 0 0 0 3 units lattice
create_atoms 1 region PtDrop
pair_style eam/alloy
pair_coeff * * Pt.lammps.eam_alloy Pt

neighbor 0.5 bin

velocity all create 0.0 1
fix 1 all nve

log log.mylog.lammps

compute myMSD all msd
dump dumpmyMSD all custom 1000 msd.lammpsdump c_myMSD[1] c_myMSD[2] c_myMSD[3]

timestep 0.001

Read Section 4.15 of the manual. Compute msd calcalutes
a handful of global values. You cannot write them to a dump
file as per-atom values. Maybe you want to use compute displace/atom
instead which will give you the displacement of each atom, which can
be written to a file.