Isn't this funny? Since I forgot the right names for all this stuff, I have to look some things up. So I was in the middle of writing a reply to you, and it hit on me that what I was trying to talk about is known in physics as the 'tau' direction. I wasn't sure so I decided to look up the net, and to my amazement the first page I hit was about a guy saying exactly the same thing I'm saying.
You may want to look at this page, it says exactly the same thing I'm trying to say:
Or perhaps this alone will do (a quote from the site):
" Einstein's derivation of the x' transform is invalid by reduction to the absurd; the transform depends on the direction of the light movement in the time term substituted for t in the X'=c*tau equation, an absolute violation of the principles of Special Relativity. It is one thing to realize that an expression in one case differs from the other, but a very different thing to let your one and only transform formula's derivation depend on an arbitrary choice of just one light direction. " (end quote)
But Einstein was not a fool, he had a problem he thought was impossible to solve, which was the lack of an absolute reference. However, he himself hinted at the solution, only failed to fully realize it. I can guarantee that a solution exists, I found it myself and it's quite possible that a lot of other people found it too.