Trouble with write_data command

I have been trying to create a series of simulations and am starting from a simple level. I have been having trouble creating a datafile with the write_data command for some reason. I am completely stumped on this one, have I failed to meet the requirement:

“system must be ready to perform a simulation before using this command (force fields setup, atom masses initialized, etc).”

Can anyone tell me why the simple script:

units metal
dimension 3
boundary p p p
atom_style atomic

lattice fcc 4.05
region box block 0 10 0 10 0 10
create_box 1 box
create_atoms 1 box

pair_style eam/alloy
pair_coeff * * Al99.eam.alloy Al

compute csym all centro/atom fcc
compute pe all pe/atom

write_data data.restart

I am getting the error message:

ERROR: Unknown command: write_data data.restart (input.cpp:204)