invalid thermo keyword in variable formula

Dear LAMMPS developers,

there are some lines from my input script:

thermo 1000

restart 10000 …

run 20000
(relaxation process)

read_restart …
reset_timestep 0

thermo 1000
thermo_style …

restart 10000

lable 1
variable i loop 1000
change_box all z scale 1.0001
run 1000
next i
jump in 1

This is a uniaxial tensile simulation, and every time the run-time error is “invalid thermo keyword in variable formula”. If I change the red line to “thermo 100”, then when the thermo output comes to the 1000th timesteps the same error warning appears, why? Is there any problem with the loop state?

Thank you so much!
best regards,
Michelle