[solved] SD Logger creates File but can't open it again

I am planning to build a System that logs Data from an accelerometer on a SD Card and an Arduino UNO.
Atm I try to get the SD logger working shown below:
http://www.ebay.de/itm/SD-Memory-Card-Module-Slot-SPI-Reader-For-Arduino-ARM-MCU-3-3V-5V-CP09001-B41-/271327231335?pt=Wissenschaftliche_Geräte&hash=item3f2c5cfd67

My sketch right now shall only create a file called “data.txt” and write a “10” into it.
What it actually does is to create the file, it gives out the “10” at the serial monitor at the FIRST run only but it does not write anything into the file. I have formatted the SD several times with different Programs and just don’t know out anymore. :~

Dataloggerlight.ino (1.8 KB)

How are you powering the card?

That SD card does not have a logic level converter, and that has been known to cause problems on 5v Arduinos.

I am powering it at the 5V port like described at the beginning of the example sketch. Does your presumption mean I can't run my SD card with my UNO R2?

Thanks for the food for thought, SurferTim!

I plugged it to the 3,3V port and now it seems to work properly. For everyone else who uses the UNO and a SD Breakboard: don't use the 5V port for it...