Ok true caesar, it's based on yours. However like slennox said, it's a substantial transformation. You say "He changed the name, some variables, but the script is the same I've made for about 90%" ...
Well just look at it and you'll see that many code is changed, removed or added.
And by the way, the variable names that you used are not changed

...
Sorry to say this, but your script had many bugs and was certainly incomplete!! And the 90%, ... I think 50% would be more correct.
However even if it's "only" 50%, you should be credited. I agree with that.