You combine a dir and a filename.
But this "SD.exists((" and "SD.open((" have double parentheses, that is very weird. Are you used with another programming language ?
Please read how to use them:http://arduino.cc/en/Reference/SDexistshttp://arduino.cc/en/Reference/SDopen
You could make a buffer and use strcat() to create the full filename with path. You have to use a '/' between them. I checked my code, and I have something like this: "/ARDUINO/LOG.TXT"
Thnx for help, i will look intro it
And no i am not commen, to programma anymore. I programmed 15years ago in c++. im try to learn the c code again