Sorry, but your problem does not imply a bug in PHP itself.  For a
list of more appropriate places to ask for help using PHP, please
visit http://www.php.net/support.php as this bug system is not the
appropriate forum for asking support questions. 

Thank you for your interest in PHP.

Use var_dump($_POST); and you'll see that variables are on their places.
Debug you code.

I use var_dump($_POST);

I think you do not understand my request.
Error message displayed are good.

The problem is that I put a value on the first field and after the POST all others fields are filled with this same value. Normally, thez should be empty or on error.

I think there is a bug :
If you put "a" on the first field, all the post displayed by the var_dump are good but the values displayed by the dynamic construction of the variables are wrong.

I don't understand why the result is correct is I use a static name for my variables and the result is different if I use a dynamic name.

Please try again my example and see !

May be it is not a bug concerning the POST but a bug concerning dynamic variables.

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

There *is* a bug in your code, so the bug system is not the place to dsicuss this.  Post your problem (and your failing code) to the php-general list, and someone (maybe even me!) might help out.