# Confusion regarding Laplace transform calculation in MATLAB

I am trying to learn about Laplace transform and especially about ROC and i found out on this weblink.

I have also attached a snapshot of this link and highlighted where it is being said that although the signals are differing, their Laplace Transforms are identical

My MATLAB code

clc
clear
close all
syms s t a
x1=exp(-a*t)*heaviside(t)
x2=-exp(-a*t).*heaviside(-t)
X1=laplace(x1,s)
X2=laplace(x2,s)


When i run above script i get X2=0, but as per above mentioned web link , i should have got $$1/(s+a)$$

Why i am getting different values of X1 and X2?

I have also attached snapshot of above weblink

Since $$x_2(t)$$ is zero for $$t\gt0$$, the result of the uni-lateral Laplace transform must be zero.