Constants my only contain - boolean, integer, float and string data. DOCUMENT_ROOT refers to a variable (the proper way to refer to it is $_SERVER['DOCUMENT_ROOT']) and you cannot make a defined constant the way it is.
Edit: Actually, if you do the following, the define does what you want it to -
Edit2: Because your define has a trailing slash "rqf/" when you combine this with the "/Statement.php" you will end up with two slashes.
When in doubt what a constant or variable contains, echo it to make sure it contains the expected contents.