A sviour problem while installing and running julia atom

Dear colleagues
I installed Julia Atom in my window 10. When I tried to run my program it gave the following error. I have run this programm in my Proffessors laptop, but here it does not. Can anyone help me regarding this?

LoadError: UndefVarError: x_star not defined
in expression starting at E:\4-IEEE Papers\2018\Conferences Papers\2018\CINTI-2018\CINTI2018-1st Paper\FitzHugh_Nagumo.jl:20
top-level scope at FitzHugh_Nagumo.jl:21 [inlined]
top-level scope at none:0

Hi. You have to show us the code you tried to run.