Using the POST method cause cutting the first character 
from the name of the form control. Using the GET method works as expected (no cutting).

example:
<FORM METHOD=POST ACTION="debug.php">
<INPUT TYPE="submit" NAME="action" VALUE="val">
</FORM>

gives result:
    [_POST] => Array
        (
            [ction] => val
        )

quick-fix:
just prefix all NAMEs with any char 
(NAME="action" becomes NAME="_action")