[SR] Why?

One of the fundamental equations of the theory of relativity, To²=Tr²+Et², probably even one of the most beautiful in all of science, will however pose a small problem for a few months to the greatest theorist of our time: the doctor Richard Hachel.
A problem will appear to emerge in the development of uniformly accelerated frames of reference, because if we set x=(1/2.a.Tr²+Vr.Tr) it no longer works.
Now, if we look closely, reason makes us laugh.
My dear friends, do you understand WHY, in this specific case it does not work.
WHY? The answer is obvious if you correctly understand the theory of relativity. That is to say if anyone read me.
If you haven't read me, you can't understand. Whether we think we're the biggest name in RR or whether we're called Poincaré or Einstein.
Who can answer me (since some people have to read me and understand the SR in more depth).
R.H.