Symmetric property of an equivalence relation states that if $a$~$b$ then

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Symmetric property of an equivalence relation states that if $a$~$b$ then $b$~$a$; Transitive property states that if $a$~$b$ and $b$~$c$ then $a$~$c$. What is wrong with the following proof that symmetric and transitive property imply reflexive property ? Let $a$~$b$; then $b$~$a$, whence, by property of transitivity
(using $a = c$), $a$~$a$.(,where '~' denotes a binary relation ).

Is there any alternative of reflexive property which will insure that properties of symmetricity and transitivity imply property of reflexivity ?