Alright, after builidng it like done on the first post but using the same pins as in your post i was finally able to get to the point that the Serial window says: Done!
Unfortunately 'Done' is not exactly anything.. although it finds the file (or not) nothing is written into it ><
SDCard is formatted in FAT with 2GB Space - everything that is on it is just the 0byte data.txt
edit sectorsavailable() return 0
edit2 you may chose to ignore the whole post.. somehow it seems my SD card is done with the world ;0) - it cant be written with anything ><