Question: Simplification of the representation of Dirac and Heaviside functions

I have a trouble of Maple.
I can't understand the solution of Maple for simplification of Dirac and Heaviside functions.

I wrote the below code,


Then, Maple return the answer of this code, "Dirac(x)*f(0)".
I could understand this solution, then I rewrote the next code,


Then, Maple returned "1", because I set the value of Heaviside's step function H(x) at x=0.
Finally, I wrote the below code, but there was a problem, I think.


The solution of Maple was "0".

According to my first code, I think this solution is Dirac(x)*Heaviside(0), that is, Dirac(x).
I can't understand this result.
Someone help me, please.


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